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Sample records for h2 gas separations

  1. Evaluation of an electrochemical N2/H2 gas separator

    NASA Technical Reports Server (NTRS)

    Marshall, R. D.; Wynveen, R. A.; Carlson, J. N.

    1973-01-01

    A program was successfully completed to evaluate an electrochemical nitrogen/hydrogen (N2/H2) separator for use in a spacecraft nitrogen (N2) generator. Based on the technical data obtained a N2/H2 separator subsystem consisting of an organic polymer gas permeator first stage and an electrochemical second and third stage was estimated to have the lowest total spared equivalent weight, 257 kg (566 lb), for a 15 lb/day N2 generation rate. A pre-design analysis of the electrochemical N2/H2 separator revealed that its use as a first stage resulted in too high a power requirement to be competitive with the organic polymer membrane and the palladium-silver membrane separation methods. As a result, program emphasis was placed on evaluating the electrochemical. A parametric test program characterized cell performance and established second- and third-stage electrochemical N2/H2 separator operating conditions. A design verification test was completed on the second and third stages. The second stage was then successfully endurance tested for 200 hours.

  2. Gas separating

    DOEpatents

    Gollan, Arye Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  3. Gas separating

    DOEpatents

    Gollan, Arye

    1988-01-01

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  4. Gas separating

    DOEpatents

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  5. Gas separating

    DOEpatents

    Gollan, A.Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  6. Glitters of warm H2 in cold diffuse molecular gas

    NASA Astrophysics Data System (ADS)

    Falgarone, Edith; Boulanger, Francois; Combes, Francoise; Pineau Des Forets, Guillaume; Verstraete, Laurent

    2007-05-01

    Cold molecular hydrogen, a dominant gas fraction in galaxies, does not radiate due to the symmetry of the molecule. The only tracers of cold H2, the rotational lines of CO and dust thermal emission operate only in metal-rich environments. By detecting the lowest rotational lines of H2 at unexpected levels in the cold diffuse medium of the Galaxy, ISO-SWS has challenged the traditional view of the interstellar medium (ISM) by possibly revealing the existence of tiny gas fractions within the cold ISM, warm enough to excite H2 lines. The heating source of H2 there is the intermittent dissipation of supersonic turbulence, pervading the entire ISM. These glitters of H2 line emission may become the unique tracers of cold H2 in low metallicity environments. Given the fundamental importance of probing large hidden masses of gas in galaxies, for their implication on galaxy dynamics, star formation thresholds in metal-poor environments, and the hypothesis of H2 as baryonic dark matter in galaxies, the present SST/IRS proposal is dedicated to further search of this still elusive emission. The proposed observations consist in several IRS LL pointings along the major axis of two external galaxies with massive HI disks extending far beyond their optical radius, and for which the HI rotation curve cannot be accounted for by the stellar and visible gas components. These spectra also observed in the direction of the galaxy nuclei, are meant to allow the separation between the H2 emission with stellar-type excitation from that originating in gas heated by turbulence dissipation. The goal of the proposal is to strenghten the existence of pockets of warm H2 disseminated in the cold diffuse medium of galaxies. These glitters of warm H2 would be a new tracer of hitherto undetected amounts of cold H2 in low metallicity environments, and, as a more exploratory facet, might probe the presence of large amounts of baryonic dark matter in galaxies in the form of cold molecular hydrogen.

  7. Mixed-Matric Membranes for CO2 and H2 Gas Separations Using Metal-Organic Framework and Mesoporus Hybrid Silicas

    SciTech Connect

    Inga Musselman; Kenneth Balkus, Jr.; John Ferraris

    2009-01-07

    In this work, we have investigated the separation performance of polymer-based mixed-matrix membranes containing metal-organic frameworks and mesoporous hybrid silicas. The MOF/Matrimid{reg_sign} and MOP-18/Matrimid{reg_sign} membranes exhibited improved dispersion and mechanical strength that allowed high additive loadings with reduced aggregation, as is the case of the 80 wt% MOP-18/Matrimid{reg_sign} and the 80% (w/w) Cu-MOF/Matrimid{reg_sign} membranes. Membranes with up to 60% (w/w) ZIF-8 content exhibited similar mechanical strength and improved dispersion. The H{sub 2}/CO{sub 2} separation properties of MOF/Matrimid{reg_sign} mixed-matrix membranes was improved by either keeping the selectivity constant and increasing the permeability (MOF-5, Cu-MOF) or by improving both selectivity and permeability (ZIF-8). In the case of MOF-5/Matrimid{reg_sign} mixed-matrix membranes, the H{sub 2}/CO{sub 2} selectivity was kept at 2.6 and the H{sub 2} permeability increased from 24.4 to 53.8 Barrers. For the Cu-MOF/Matrimid{reg_sign} mixed-matrix membranes, the H{sub 2}/CO{sub 2} selectivity was kept at 2.05 and the H{sub 2} permeability increased from 17.1 to 158 Barrers. These two materials introduced porosity and uniform paths that enhanced the gas transport in the membranes. When ZIF-8/Matrimid{reg_sign} mixed-matrix membranes were studied, the H{sub 2}/CO{sub 2} selectivity increased from 2.9 to 4.4 and the permeability of H{sub 2} increased from 26.5 to 35.8 Barrers. The increased H{sub 2}/CO{sub 2} selectivity in ZIF-8/Matrimid{reg_sign} membranes was explained by the sieving effect introduced by the ZIF-8 crystals (pore window 0.34 nm) that restricted the transport of molecules larger than H{sub 2}. Materials with microporous and/or mesoporous cavities like carbon aerogel composites with zeolite A and zeolite Y, and membranes containing mesoporous ZSM-5 showed sieving effects for small molecules (e.g. H{sub 2} and CO{sub 2}), however, the membranes were most

  8. Ni-H2 cell separator matrix engineering

    NASA Technical Reports Server (NTRS)

    Scott, W. E.

    1992-01-01

    This project was initiated to develop alternative separator materials to the previously used asbestos matrices which were removed from the market for health and environmental reasons. The objective of the research was to find a material or combination of materials that had the following characteristics: (1) resistant to the severe conditions encountered in Ni-H2 cells; (2) satisfactory electrical, electrolyte management, and thermal management properties to function properly; (3) environmentally benign; and (4) capable of being manufactured into a separator matrix. During the course of the research it was discovered that separators prepared from wettable polyethylene fibers along and in combination with potassium titanate pigment performed satisfactory in preliminary characterization tests. Further studies lead to the optimization of the separator composition and manufacturing process. Single ply separator sheets were manufactured with 100 percent polyethylene fibers and also with a combination of polyethylene fibers and potassium titanate pigment (PKT) in the ratio of 60 percent PKT and 40 percent fibers. A pilot paper machine was used to produce the experimental separator material by a continuous, wet laid process. Both types of matrices were produced at several different area densities (grams/sq m).

  9. Highly Selective H2 Separation Zeolite Membranes for Coal Gasification Membrane Reactor Applications

    SciTech Connect

    Mei Hong; Richard Noble; John Falconer

    2007-09-24

    Zeolite membranes are thermally, chemically, and mechanically stable. They also have tunable molecular sieving and catalytic ability. These unique properties make zeolite membrane an excellent candidate for use in catalytic membrane reactor applications related to coal conversion and gasification, which need high temperature and high pressure range separation in chemically challenging environment where existing technologies are inefficient or unable to operate. Small pore, good quality, and thin zeolite membranes are needed for highly selective H2 separation from other light gases (CO2, CH4, CO). However, current zeolite membranes have either too big zeolite pores or a large number of defects and have not been successful for H2 separation from light gases. The objective of this study is to develop zeolite membranes that are more suitable for H2 separation. In an effort to tune the size of zeolite pores and/or to decrease the number of defects, medium-pore zeolite B-ZSM-5 (MFI) membranes were synthesized and silylated. Silylation on B-ZSM-5 crystals reduced MFI-zeolite pore volume, but had little effect on CO2 and CH4 adsorption. Silylation on B-ZSM-5 membranes increased H2 selectivity both in single component and in mixtures with CO2, CH4, or N2. Single gas and binary mixtures of H2/CO2 and H2/CH4 were permeated through silylated B-ZSM-5 membranes at feed pressures up to 1.7 MPa and temperatures up to 773 K. For one B-ZSM-5 membrane after silylation, the H2/CO2 separation selectivity at 473 K increased from 1.4 to 37, whereas the H2/CH4 separation selectivity increased from 1.6 to 33. Hydrogen permeance through a silylated BZSM-5 membrane was activated with activation energy of {approx}10 kJ/mol, but the CO2 and CH4 permeances decreased slightly with temperature in both single gas and in mixtures. Therefore, the H2 permeance and H2/CO2 and H2/CH4 separation selectivities increased with temperature. At 673 K, the H2 permeance was 1.0x10-7 mol{center_dot}m-2{center

  10. Removal of Boron in Silicon by H2-H2O Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Andersson, Stefan; Nordstrand, Erlend; Tangstad, Merete

    2012-08-01

    The removal of boron in pure silicon by gas mixtures has been examined in the laboratory. Water-vapor-saturated hydrogen was used to remove boron doped in electronic-grade silicon in a vacuum frequency furnace. Boron concentrations in silicon were reduced from 52 ppm initially to 0.7 ppm and 3.4 ppm at 1450°C and 1500°C, respectively, after blowing a H2-3.2%H2O gas mixture for 180 min. The experimental results indicate that the boron removal as a function of gas-blowing time follows the law of exponential decay. After 99% of the boron is removed, approximately 90% of the silicon can be recovered. In order to better understand the gaseous refining mechanism, the quantum chemical coupled cluster with single and double excitations and a perturbative treatment of triple excitations method was used to accurately predict the enthalpy and entropy of formation of the HBO molecule. A simple refining model was then used to describe the boron refining process. This model can be used to optimize the refining efficiency.

  11. Asymmetric gas separation membranes

    SciTech Connect

    Malon, R. F.; Zampini, A.

    1984-12-04

    Asymmetric gas separation membranes of materials having selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, exhibit significantly improved permeation selectivities for the at least one gas when the asymmetric membrane is contacted on one or both surfaces with an effective amount of a Lewis acid. The improved asymmetric gas separation membranes, process for producing the improved membrane, and processes utilizing such membranes for selectively separating at least one gas from a gaseous mixture by permeation are disclosed.

  12. Asymmetric gas separation membranes

    SciTech Connect

    Malon, R. F.; Zampini, A.

    1984-09-18

    Asymmetric gas separation membranes of materials having selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, exhibit significantly improved permeation selectivities for the at least one gas when the asymmetric membrane is contacted on one or both surfaces with an effective amount of a Br nsted-Lowry acid. The improved asymmetric gas separation membranes, process for producing the improved membrane, and processes utilizing such membranes for selectively separating at least one gas from a gaseous mixture by permeation are disclosed.

  13. A Model of Gas Recycling Based on Condensed H2

    NASA Astrophysics Data System (ADS)

    Pfenniger, D.

    2004-06-01

    To address, among other questions, puzzling observations about star forming in the extreme outer HI disk of M 31 (Cuillandre et al. 2001), a scenario of interstellar gas cycling between the visible and a very cold invisible phase is investigated. The key new element sketched here, allowing to maintain the bulk of the gas out of sight, is that molecular hydrogen becomes liquid or solid below 33 K at sufficiently high pressure, allowing AU-sized spheres of very cold gas to be stabilised by incompressible cores of condensed H2 (Pfenniger 2004). These predicted cold gas globules are relatively weakly bound (˜ 10-3 eV/nucleon), such that their lifetime depends directly on the ambient UV/CR excitation level. At galactic scale the globules behave as collisionless bodies, and evaporate and become the usual visible ISM gas through heating. Much of the ISM gas can thus spend a long time in this cold condensed phase in low excitation regions. N-body simulations of galactic disks modeling such effects have been run, and some of their features are described in more detail in this volume and elsewhere (Revaz & Pfenniger 2004).

  14. NOVEL NANOCOMPOSITE MEMBRANE STRUCTURES FOR H2 SEPARATIONS

    SciTech Connect

    Benny D. Freeman

    2005-03-31

    This report explores possible methods of improving CO{sub 2} selectivity in polymer based membranes. The first method investigated using basic nanoparticles to enhance the solubility of acid gases in nanocomposite membranes, thus enhancing the overall acid gas/light gas selectivity (e.g., CO{sub 2}/H{sub 2}, CO{sub 2}/CH{sub 4}, etc.). The influence of nanoparticle surface chemistry on nanocomposite morphology and transport properties will be determined experimentally in a series of poly(1-trimethylsilyl-1-propyne). Additional factors (e.g., chemical reaction of the particles with the polymers) have been considered, as necessary, during the course of the investigation. The second method investigated using polar polymers such as crosslinked poly(ethylene oxide) and poly(ether-b-amide) to improve CO{sub 2} sorption and thereby increase CO{sub 2} permeability and CO{sub 2}/light gas selectivity. For both types of materials, CO{sub 2} and light gas permeabilities have been characterized. The overall objective was to improve the understanding of materials design strategies to improve acid gas transport properties of membranes.

  15. Enhanced photo-H2 production of R. faecalis RLD-53 by separation of CO2 from reaction system.

    PubMed

    Liu, Bing-Feng; Ren, Nan-Qi; Ding, Jie; Xie, Guo-Jun; Cao, Guang-Li

    2009-02-01

    The effect of different gases, CO(2) concentration, and separation of CO(2) from reaction system on photo-fermentation H(2) production was investigated by batch culture in this study. Experimental results showed that different gases (Ar,N(2),CO(2), and air) as gas phase have obviously affected on photo-H(2) production and a high concentration of CO(2) can inhibit the growth and H(2) evolution of Rhodopseudomonas faecalis RLD-53. When CO(2) concentration at 5%, cell increased most rapidly the specific growth rate of 0.489 g/l/h and the specific growth rate fell to be 0.265 g/l/h when CO(2) concentration at 40%. However, the growth of RLD-53 at CO(2) concentration of 60-100% was almost completely inhibited. At CO(2) concentrations of 5% and 10%, the maximum H(2) yield was 2.54 and 2.59 mol-H(2)/mol acetate, respectively, and it was similar with the control (2.61 mol-H(2)/mol acetate). H(2) not produced when CO(2) concentration at 60-100%. In conclusion, separation of CO(2) from reaction system can stimulate H(2) production in the entire photo-H(2) production process and H(2) yield increased about 12.8-18.85% than the control.

  16. Gas separation membranes

    DOEpatents

    Schell, William J.

    1979-01-01

    A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

  17. Fabrication of COF-MOF Composite Membranes and Their Highly Selective Separation of H2/CO2.

    PubMed

    Fu, Jingru; Das, Saikat; Xing, Guolong; Ben, Teng; Valtchev, Valentin; Qiu, Shilun

    2016-06-22

    The search for new types of membrane materials has been of continuous interest in both academia and industry, given their importance in a plethora of applications, particularly for energy-efficient separation technology. In this contribution, we demonstrate for the first time that a metal-organic framework (MOF) can be grown on the covalent-organic framework (COF) membrane to fabricate COF-MOF composite membranes. The resultant COF-MOF composite membranes demonstrate higher separation selectivity of H2/CO2 gas mixtures than the individual COF and MOF membranes. A sound proof for the synergy between two porous materials is the fact that the COF-MOF composite membranes surpass the Robeson upper bound of polymer membranes for mixture separation of a H2/CO2 gas pair and are among the best gas separation MOF membranes reported thus far.

  18. Polymide gas separation membranes

    DOEpatents

    Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz

    2004-09-14

    Soluble polyamic acid salt (PAAS) precursors comprised of tertiary and quaternary amines, ammonium cations, sulfonium cations, or phosphonium cations, are prepared and fabricated into membranes that are subsequently imidized and converted into rigid-rod polyimide articles, such as membranes with desirable gas separation properties. A method of enhancing solubility of PAAS polymers in alcohols is also disclosed.

  19. Highly Selective H2 Separation Zeolite Membranes for Coal Gasification Membrane Reactor Applications

    SciTech Connect

    Mei Hong; Richard D. Noble; John L. Falconer

    2006-09-24

    Zeolite membranes are thermally, chemically, and mechanically stable. They also have tunable molecular sieving and catalytic ability. These unique properties make zeolite membrane an excellent candidate for use in catalytic membrane reactor applications related to coal conversion and gasification, which need high temperature and high pressure range separation in chemically challenging environment where existing technologies are inefficient or unable to operate. Small pore, good quality, and thin zeolite membranes are needed for highly selective H{sub 2} separation from other light gases (CO{sub 2}, CH{sub 4}, CO). However, zeolite membranes have not been successful for H{sub 2} separation from light gases because the zeolite pores are either too big or the membranes have a large number of defects. The objective of this study is to develop zeolite membranes that are more suitable for H{sub 2} separation. In an effort to tune the size of zeolite pores and/or to decrease the number of defects, medium-pore zeolite B-ZSM-5 (MFI) membranes were synthesized and silylated. Silylation on B-ZSM-5 crystals reduced MFI-zeolite pore volume, but had little effect on CO{sub 2} and CH{sub 4} adsorption. Silylation on B-ZSM-5 membranes increased H{sub 2} selectivity both in single component and in mixtures with CO{sub 2}CO{sub 2}, CH{sub 4}, or N2. Single gas and binary mixtures of H{sub 2}/CO{sub 2} and H{sub 2}/CH{sub 4} were separated through silylated B-ZSM-5 membranes at feed pressures up to 1.7 MPa and temperatures up to 773 K. For one BZSM-5 membrane after silylation, the H2/CO{sub 2} separation selectivity at 473 K increased from 1.4 to 37, whereas the H{sub 2}/CH{sub 4} separation selectivity increased from 1.6 to 33. Hydrogen permeance through a silylated B-ZSM-5 membrane was activated, but the CO{sub 2} and CH4 permeances decreased slightly with temperature in both single gas and in mixtures. Therefore, the H{sub 2} permeance and H{sub 2}/CO{sub 2} and H{sup 2} /CH{sub 4

  20. Thermal Pressure in Diffuse H2 Gas Measured by Herschel [C II] Emission and FUSE UV H2 Absorption

    NASA Astrophysics Data System (ADS)

    Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.

    2017-04-01

    UV absorption studies with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite have made important observations of H2 molecular gas in Galactic interstellar translucent and diffuse clouds. Observations of the 158 μm [C ii] fine-structure line with Herschel trace the same H2 molecular gas in emission. We present [C ii] observations along 27 lines of sight (LOSs) toward target stars of which 25 have FUSE H2 UV absorption. Two stars have only HST STIS C ii λ2325 absorption data. We detect [C ii] 158 μm emission features in all but one target LOS. For three target LOSs that are close to the Galactic plane, | {\\text{}}b| < 1°, we also present position–velocity maps of [C ii] emission observed by Herschel Heterodyne Instrument in the Far Infrared (HIFI) in on-the-fly spectral-line mapping. We use the velocity-resolved [C ii] spectra observed by the HIFI instrument toward the target LOSs observed by FUSE to identify [C ii] velocity components associated with the H2 clouds. We analyze the observed velocity integrated [C ii] spectral-line intensities in terms of the densities and thermal pressures in the H2 gas using the H2 column densities and temperatures measured by the UV absorption data. We present the H2 gas densities and thermal pressures for 26 target LOSs and from the [C ii] intensities derive a mean thermal pressure in the range of ∼6100–7700 K cm‑3 in diffuse H2 clouds. We discuss the thermal pressures and densities toward 14 targets, comparing them to results obtained using the UV absorption data for two other tracers C i and CO. Our results demonstrate the richness of the far-IR [C ii] spectral data which is a valuable complement to the UV H2 absorption data for studying diffuse H2 molecular clouds. While the UV absorption is restricted to the directions of the target star, far-IR [C ii] line emission offers an opportunity to employ velocity-resolved spectral-line mapping capability to study in detail the clouds’ spatial and velocity

  1. Gas separation membrane module assembly

    DOEpatents

    Wynn, Nicholas P; Fulton, Donald A.

    2009-03-31

    A gas-separation membrane module assembly and a gas-separation process using the assembly. The assembly includes a set of tubes, each containing gas-separation membranes, arranged within a housing. The housing contains a tube sheet that divides the space within the housing into two gas-tight spaces. A permeate collection system within the housing gathers permeate gas from the tubes for discharge from the housing.

  2. Amine-bearing mesoporous silica for CO(2) and H(2)S removal from natural gas and biogas.

    PubMed

    Belmabkhout, Youssef; De Weireld, Guy; Sayari, Abdelhamid

    2009-12-01

    Triamine-grafted pore-expanded mesoporous silica (TRI-PE-MCM-41) exhibited high CO(2) and H(2)S adsorption capacity as well as high selectivity toward acid gases versus CH(4). Unlike physical adsorbents such as zeolites and activated carbons, the presence of moisture in the feed enhanced the CO(2) removal capability of TRI-PE-MCM-41 without altering its H(2)S adsorption capacity. Thus, depending on the feed composition, CO(2) and H(2)S may be removed over TRI-PE-MCM-41 simultaneously or sequentially. These findings are suitable for acid gas separation from CH(4)-containing mixtures such as natural gas and biogas.

  3. Corrosion of 310 stainless steel in H2-H2O-H2S gas mixtures: Studies at constant temperature and fixed oxygen potential

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Jacob, K. T.; Nelson, H. G.

    1981-01-01

    Corrosion of SAE 310 stainless steel in H2-H2O-H2S gas mixtures was studied at a constant temperature of 1150 K. Reactive gas mixtures were chosen to yield a constant oxygen potential of approximately 6 x 10 to the minus 13th power/cu Nm and sulfur potentials ranging from 0.19 x 10 to the minus 2nd power/cu Nm to 33 x 10 to the minus 2nd power/cu Nm. The kinetics of corrosion were determined using a thermobalance, and the scales were analyzed using metallography, scanning electron microscopy, and energy dispersive X-ray analysis. Two corrosion regimes, which were dependent on sulfur potential, were identified. At high sulfur potentials (p sub S sub 2 less than or equal to 2.7 x 10 to the minus 2nd power/cu Nm) the corrosion rates were high, the kinetics obeyed a linear rate equation, and the scales consisted mainly of sulfide phases similar to those observed from pure sulfication. At low sulfur potentials (P sub S sub 2 less than or equal to 0.19 x 10 to the minus 2nd power/cu Nm) the corrosion rates were low, the kinetics obeyed a parabolic rate equation, and scales consisted mainly of oxide phases.

  4. Removal of H2S from gas stream using combined plasma photolysis technique at atmospheric pressure.

    PubMed

    Huang, Li; Xia, Lanyan; Ge, Xiaoxue; Jing, Hengye; Dong, Wenbo; Hou, Huiqi

    2012-06-01

    In this paper, H(2)S in gas stream was successfully decomposed at atmospheric pressure by dielectric barrier discharge plasma and VUV-UV radiation from a combined plasma photolysis reactor (CDBD). In comparison with DBD, CDBD enhanced H(2)S removal efficiency significantly at the same applied voltage, inlet H(2)S concentration and gas residence time. H(2)S removal efficiency was determined as a function of Kr pressure, applied voltage, inlet H(2)S concentration, and gas residence time. H(2)S removal efficiency could reach as high as 93% at inlet H(2)S concentration of 27.1 mg m(-3), residence time of 0.4 s, and applied voltage of 7.5 kV. The main products were discerned as H(2)O and SO(4)(2-) based on FTIR and IC analysis.

  5. Gas-Phase Photochemical Overall H2 S Splitting by UV Light Irradiation.

    PubMed

    Baldovi, Herme G; Albero, Josep; Ferrer, Belen; Mateo, Diego; Alvaro, Mercedes; García, Hermenegildo

    2017-04-11

    Splitting of hydrogen sulfide is achieved to produce value-added chemicals. Upon irradiation at 254 nm in the gas phase and in the absence of catalysts or photocatalysts at near room temperature, H2 S splits into stoichiometric amounts of H2 and S with a quantum efficiency close to 50 %. No influence of the presence of CH4 and CO2 (typical components in natural gas and biogas in which H2 S is an unwanted component) on the efficiency of overall H2 S splitting was observed. A mechanism for the H2 and S formation is proposed.

  6. Update on DOE Advanced IGCC/H2 Gas Turbine

    NASA Technical Reports Server (NTRS)

    Chupp, Ray

    2009-01-01

    Cooling Flow Reduction: a) Focus on improving turbine hot gas path part cooling efficiency. b) Applicable to current metallic turbine components and synergistic with advanced materials. c) Address challenges of IGCC/hydrogen fuel environment (for example, possible cooling hole plugging). Leakage Flow Reduction: a) Focus on decreasing turbine parasitic leakages, i.e. between static-to-static, static-to-rotating turbine parts. b) Develop improved seal designs in a variety of important areas. Purge Flow Reduction: a) Focus on decreasing required flows to keep rotor disk cavities within temperature limits. b) Develop improved sealing at the cavity rims and modified flow geometries to minimize hot gas ingestion and aerodynamic impact.

  7. Advanced H2-HCl Gas Dynamic Laser, Phase 2

    DTIC Science & Technology

    1976-01-01

    available in limited quantities on a special order basis, but synthesis is a straightforward and a well-known process. Three candidate propellant...oxidizers. Both oxides react significantly with HL and HC1 at high temperatures to yield H20 and other contaminants (Ca, Mg, CaOH , MgOH, CaCl, CaCl2, MgCip...quantities. However, synthesis of this compound is straight forward and results in a product of good yield and high purity. It is the best H„ gas generator

  8. Phase Separation Kinetics in Isopycnic Mixtures of H2O/CO2/Ethoxylated Alcohol Surfactants

    NASA Technical Reports Server (NTRS)

    Lesemann, Markus; Paulaitis, Michael E.; Kaler, Eric W.

    1999-01-01

    Ternary mixtures of H2O and CO2 with ethoxylated alcohol (C(sub i)E(sub j)) surfactants form three coexisting liquid phases at conditions where two of the phases have equal densities (isopycnic phases). Isopycnic phase behavior has been observed for mixtures containing C8E5, C10E6, and C12E6 surfactants, but not for those mixtures containing either C4E1 or C8E3 surfactants. Pressure-temperature (PT) projections for this three-phase equilibrium were determined for H2O/CO2/C8E5 and H2O/CO2/C10E6 mixtures at temperatures from approximately 25 to 33 C and pressures between 90 and 350 bar. Measurements of the microstructure in H2O/CO2/C12E6 mixtures as a function of temperature (25-31 C), pressure (63.1-90.7 bar), and CO2 composition (0-3.9 wt%) have also been carried out to show that while micellar structure remains essentially un-changed, critical concentration fluctuations increase as the phase boundary and plait point are approached. In this report, we present our first measurements of the kinetics of isopycnic phase separation for ternary mixtures of H2O/CO2/C8E5.

  9. Hydrogen sulfide (H2S) and sour gas effects on the eye. A historical perspective.

    PubMed

    Lambert, Timothy William; Goodwin, Verona Marie; Stefani, Dennis; Strosher, Lisa

    2006-08-15

    The toxicology of hydrogen sulfide (H(2)S) and sour gas on the eye has a long history beginning at least with Ramazzini's observations [Ramazzini B. Diseases of Workers--De Morbis Artificum Diatriba--1713. Wright WC (trans). New York, C. Hafner Publishing Co Inc.; 1964. 98-99 pp.]. In contrast, a recent review by Alberta Health and Wellness (AHW Report) concluded that there is little evidence of eye irritation following short-term exposures to H(2)S at concentrations up to 100ppm and that the H(2)S literature on the eye is a series of unsubstantiated claims reproduced in review articles dating back to the 1930s [Alberta Health and Wellness (AHW report). Health effects associated with short-term exposure to low levels of hydrogen sulfide: a technical review, Alberta Health and Wellness, October 2002, 81pp.]. In this paper, we evaluated this claim through a historical review of the toxicology of the eye. Ramazzini noted the effects of sewer gas on the eye [Ramazzini B. Diseases of Workers--De Morbis Artificum Diatriba--1713. Wright WC (trans). New York, C. Hafner Publishing Co Inc. 1964. 98-99 pp.]. Lehmann experimentally showed eye effects in men at 70-90ppm H(2)S and also in animals [Lehmann K. Experimentalle Studien uber den Einfluss technisch und hygienisch wichtiger Gase und Dampfe auf den Organismus. Arch Hyg 1892;14:135-189]. In 1923, Sayers, Mitchell and Yant reported eye effects in animals and men at 50ppm H(2)S. Barthelemy showed eye effects in animals and men at 20ppm H(2)S [Barthelemy HL. Ten years' experience with industrial hygiene in connection with the manufacture of viscose rayon. J Ind Hyg Toxicol 1939;21:141-51]. Masure experimentally showed that H(2)S is the causative agent of eye impacts in animals and men [Masure R. La Keratoconjunctivite des filatures de viscose; etude clinique and experiementale. Rev Belge Pathol 1950;20:297-341]. Michal upon microscopic examination of the rat's cornea, found nuclear pyknosis, edema and separation of cells in

  10. Towards H2-rich gas production from unmixed steam reforming of methane: Thermodynamic modeling

    NASA Astrophysics Data System (ADS)

    Lima da Silva, Aline; Müller, Iduvirges Lourdes

    2011-10-01

    In this work, the Gibbs energy minimization method is applied to investigate the unmixed steam reforming (USR) of methane to generate hydrogen for fuel cell application. The USR process is an advanced reforming technology that relies on the use of separate air and fuel/steam feeds to create a cyclic process. Under air flow (first half of the cycle), a bed of Ni-based material is oxidized, providing the heat necessary for the steam reforming that occurs subsequently during fuel/steam feed stage (second half of the cycle). In the presence of CaO sorbent, high purity hydrogen can be produced in a single reactor. In the first part of this work, it is demonstrated that thermodynamic predictions are consistent with experimental results from USR isothermal tests under fuel/steam feed. From this, it is also verified that the reacted NiO to CH4 (NiOreacted/CH4) molar ratio is a very important parameter that affects the product gas composition and decreases with time. At the end of fuel/steam flow, the reforming reaction is the most important chemical mechanism, with H2 production reaching ∼75 mol%. On the other hand, at the beginning of fuel/steam feed stage, NiO reduction reactions dominate the equilibrium system, resulting in high CO2 selectivity, negative steam conversion and low concentrations of H2. In the second part of this paper, the effect of NiOreacted/CH4 molar ratio on the product gas composition and enthalpy change during fuel flow is investigated at different temperatures for inlet H2O/CH4 molar ratios in the range of 1.2-4, considering the USR process operated with and without CaO sorbent. During fuel/steam feed stage, the energy demand increases as time passes, because endothermic reforming reaction becomes increasingly important as this stage nears its end. Thus, the duration of the second half of the cycle is limited by the conditions under which auto-thermal operation can be achieved. In absence of CaO, H2 at concentrations of approximately 73 mol% can

  11. Gas Separations using Ceramic Membranes

    SciTech Connect

    Paul KT Liu

    2005-01-13

    This project has been oriented toward the development of a commercially viable ceramic membrane for high temperature gas separations. A technically and commercially viable high temperature gas separation membrane and process has been developed under this project. The lab and field tests have demonstrated the operational stability, both performance and material, of the gas separation thin film, deposited upon the ceramic membrane developed. This performance reliability is built upon the ceramic membrane developed under this project as a substrate for elevated temperature operation. A comprehensive product development approach has been taken to produce an economically viable ceramic substrate, gas selective thin film and the module required to house the innovative membranes for the elevated temperature operation. Field tests have been performed to demonstrate the technical and commercial viability for (i) energy and water recovery from boiler flue gases, and (ii) hydrogen recovery from refinery waste streams using the membrane/module product developed under this project. Active commercializations effort teaming with key industrial OEMs and end users is currently underway for these applications. In addition, the gas separation membrane developed under this project has demonstrated its economical viability for the CO2 removal from subquality natural gas and landfill gas, although performance stability at the elevated temperature remains to be confirmed in the field.

  12. 30 CFR 250.1164 - What are the requirements for flaring or venting gas containing H2S?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Gas Production Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1164 What are the requirements for flaring or venting gas containing H2S? (a) You may not vent gas containing H2S, except for... Supervisor may further restrict the flaring of gas containing H2S. The Regional Supervisor will...

  13. C+/H2 gas in star-forming clouds and galaxies

    NASA Astrophysics Data System (ADS)

    Nordon, Raanan; Sternberg, Amiel

    2016-11-01

    We present analytic theory for the total column density of singly ionized carbon (C+) in the optically thick photon dominated regions (PDRs) of far-UV irradiated (star-forming) molecular clouds. We derive a simple formula for the C+ column as a function of the cloud (hydrogen) density, the far-UV field intensity, and metallicity, encompassing the wide range of galaxy conditions. When assuming the typical relation between UV and density in the cold neutral medium, the C+ column becomes a function of the metallicity alone. We verify our analysis with detailed numerical PDR models. For optically thick gas, most of the C+ column is mixed with hydrogen that is primarily molecular (H2), and this `C+/H2' gas layer accounts for almost all of the `CO-dark' molecular gas in PDRs. The C+/H2 column density is limited by dust shielding and is inversely proportional to the metallicity down to ˜0.1 solar. At lower metallicities, H2 line blocking dominates and the C+/H2 column saturates. Applying our theory to CO surveys in low-redshift spirals, we estimate the fraction of C+/H2 gas out of the total molecular gas to be typically ˜0.4. At redshifts 1 < z < 3 in massive disc galaxies the C+/H2 gas represents a very small fraction of the total molecular gas (≲ 0.16). This small fraction at high redshifts is due to the high gas surface densities when compared to local galaxies.

  14. Gas separations using inorganic membranes

    SciTech Connect

    Egan, B.Z.; Singh, S.P.N.; Fain, D.E.; Roettger, G.E.; White, D.E.

    1992-04-01

    This report summarizes the results from a research and development program to develop, fabricate, and evaluate inorganic membranes for separating gases at high temperatures and pressures in hostile process environments encountered in fossil energy conversion processes such as coal gasification. The primary emphasis of the research was on the separation and recovery of hydrogen from synthesis gas. Major aspects of the program included assessment of the worldwide research and development activity related to gas separations using inorganic membranes, identification and selection of candidate membrane materials, fabrication and characterization of membranes using porous membrane technology developed at the Oak Ridge K-25 Site, and evaluation of the separations capability of the fabricated membranes in terms of permeabilities and fluxes of gases.

  15. Asymmetric membranes for gas separations

    SciTech Connect

    Finken, H.

    1985-01-01

    Recent membrane developments for gaseous mixture separations are compared to the development of reverse osmosis membranes for water desalination. The goals of these developments have been the search for ideal permselective polymeric materials, techniques for producing ultrathin membrane layers free of imperfections and transforming gelled reverse osmosis membranes into solid gas permeation membranes. A novel approach to meeting the basic requirements of high permselectivity is attempted by altering the physical polymer structure within the membrane prior to application for gas separation. The influence of these physical interactions on membrane properties is presented. 47 references, 11 figures, 6 tables.

  16. Lighting the Dark Molecular Gas: H2 as a Direct Tracer

    NASA Astrophysics Data System (ADS)

    Togi, Aditya; Smith, J. D. T.

    2016-10-01

    Robust knowledge of molecular gas mass is critical for understanding star formation in galaxies. The {{{H}}}2 molecule does not emit efficiently in the cold interstellar medium, hence the molecular gas content of galaxies is typically inferred using indirect tracers. At low metallicity and in other extreme environments, these tracers can be subject to substantial biases. We present a new method of estimating total molecular gas mass in galaxies directly from pure mid-infrared rotational {{{H}}}2 emission. By assuming a power-law distribution of {{{H}}}2 rotational temperatures, we can accurately model {{{H}}}2 excitation and reliably obtain warm (T ≳ 100 K) {{{H}}}2 gas masses by varying only the power law’s slope. With sensitivities typical of Spitzer/IRS, we are able to directly probe the {{{H}}}2 content via rotational emission down to ∼80 K, accounting for ∼15% of the total molecular gas mass in a galaxy. By extrapolating the fitted power-law temperature distributions to a calibrated single lower cutoff temperature, the model also recovers the total molecular content within a factor of ∼2.2 in a diverse sample of galaxies, and a subset of broken power-law models performs similarly well. In ULIRGs, the fraction of warm {{{H}}}2 gas rises with dust temperature, with some dependency on α CO. In a sample of five low-metallicity galaxies ranging down to 12+{log}[{{O}}/{{H}}]=7.8, the model yields molecular masses up to ∼100× larger than implied by CO, in good agreement with other methods based on dust mass and star formation depletion timescale. This technique offers real promise for assessing molecular content in the early universe where CO and dust-based methods may fail.

  17. Phosphazene membranes for gas separations

    DOEpatents

    Stewart, Frederick F.; Harrup, Mason K.; Orme, Christopher J.; Luther, Thomas A.

    2006-07-11

    A polyphosphazene having a glass transition temperature ("T.sub.g") of approximately -20.degree. C. or less. The polyphosphazene has at least one pendant group attached to a backbone of the polyphosphazene, wherein the pendant group has no halogen atoms. In addition, no aromatic groups are attached to an oxygen atom that is bound to a phosphorus atom of the backbone. The polyphosphazene may have a T.sub.g ranging from approximately -100.degree. C. to approximately -20.degree. C. The polyphosphazene may be selected from the group consisting of poly[bis-3-phenyl-1-propoxy)phosphazene], poly[bis-(2-phenyl-1-ethoxy)phosphazene], poly[bis-(dodecanoxypolyethoxy)-phosphazene], and poly[bis-(2-(2-(2-.omega.-undecylenyloxyethoxy)ethoxy)ethoxy)phosphazene]- . The polyphosphazene may be used in a separation membrane to selectively separate individual gases from a gas mixture, such as to separate polar gases from nonpolar gases in the gas mixture.

  18. Abundant gas-phase H2O in absorption toward massive protostars

    NASA Astrophysics Data System (ADS)

    Boonman, A. M. S.; van Dishoeck, E. F.

    2003-06-01

    We present infrared spectra of gas-phase H2O around 6 mu m toward 12 deeply embedded massive protostars obtained with the Short Wavelength Spectrometer on board the Infrared Space Observatory (ISO). The nu2 ro-vibrational band has been detected toward 7 of the sources and the excitation temperatures indicate an origin in the warm gas at Tex>~ 250 K. Typical derived gas-phase H2O abundances are ~ 5*E-6-6*E-5, with the abundances increasing with the temperature of the warm gas. The inferred gas/solid ratios show a similar trend with temperature and suggest that grain-mantle evaporation is important. The increasing gas/solid ratio correlates with other indicators of increased temperatures. If the higher temperatures are due to a larger ratio of source luminosity to envelope mass, this makes gas-phase H2O a good evolutionary tracer. Comparison with chemical models shows that three different chemical processes, ice evaporation, high-T chemistry, and shocks, can reproduce the high inferred gas-phase H2O abundances. In a forthcoming paper each of these processes are investigated in more detail in comparison with data from the Long Wavelength Spectrometer on board ISO and the Submillimeter Wave Astronomy Satellite (SWAS). Comparison with existing SWAS data indicates that a jump in the H2O abundance is present and that the observed nu2 ro-vibrational band traces primarily the warm inner envelope. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

  19. Effect of H2 and CO contents in syngas during combustion using Micro Gas Turbine

    NASA Astrophysics Data System (ADS)

    Othman, N. F.; Boosroh, M. H.

    2016-03-01

    Synthetic gas or syngas is produced from the gasification process. Its main compositions are hydrogen, H2; carbon monoxide, CO; methane, CH4; carbon dioxide, CO2 and nitrogen, N2. Syngas is a substitute for the depleting natural gas (80-90%.vol. CH4). Natural gas is combusted in gas turbine in gas-fired power plant to produce electricity. However, combustion of syngas using gas turbine is expected to show different behavior compared to natural gas combustion. This is because of H2 and CO contents in syngas have higher adiabatic flame temperature than CH4. In this study, different quality of syngas with different contents of H2 (0.6-0.8 %.vol.) and CO (1-3 %.vol.) were combusted using 30kW Micro Gas Turbine (MGT). Performances of different syngas quality were studied using NOx, CO, CO2 emissions and combustion efficiency parameters. NOx and CO are the main pollutants from the combustion process. NOx emissions were the highest for syngas with H2 contents of 0.8 %.vol. and CO contents of 3 %.vol. CO emissions were in the range of 220-310 ppm for all the tested syngas. While, CO2 emissions were in the range of 0.96-1.06 % for all the tested syngas. Combustion efficiencies were reduced for syngas with CO contents of 1 %.vol. and H2 contents of 0.6-0.8 %.vol. This is most probably due to the dilution effect of N2 in syngas.

  20. Surface modifications of Cu(In ,Ga)S2 thin film solar cell absorbers by KCN and H2O2/H2SO4 treatments

    NASA Astrophysics Data System (ADS)

    Weinhardt, L.; Fuchs, O.; Groß, D.; Umbach, E.; Heske, C.; Dhere, N. G.; Kadam, A. A.; Kulkarni, S. S.

    2006-07-01

    KCN etching of the CuxS surface layer formed during the production process of Cu(In ,Ga)S2 thin film solar cell absorbers as well as subsequent H2O2/H2SO4 etching of the Cu(In ,Ga)S2 surface have been investigated using x-ray photoelectron spectroscopy, x-ray excited Auger electron spectroscopy, and x-ray emission spectroscopy. We find that the KCN etching removes the CuxS layer—being identified as Cu2S—and that there is K deposited during this step, which is removed by the subsequent H2O2/H2SO4 oxidation treatment. When a CdS buffer layer is deposited on the absorber directly after KCN etching, a K compound (KCO3) is observed at the CdS surface.

  1. Interactions of Multiple Gas-Transducing Systems: Hallmarks and Uncertainties of CO, NO, and H2S Gas Biology

    PubMed Central

    Fukuda, Ryo; Bateman, Ryon M.; Yamamoto, Takehiro

    2010-01-01

    Abstract The diverse physiological actions of the “biologic gases,” O2, CO, NO, and H2S, have attracted much interest. Initially viewed as toxic substances, CO, NO, and H2S play important roles as signaling molecules. The multiplicity of gas actions and gas targets and the difficulty in measuring local gas concentrations obscures detailed mechanisms whereby gases exert their actions, and many questions remain unanswered. It is now readily apparent, however, that heme-based proteins play central roles in gas-generation/reception mechanisms and provide a point where multiple gases can interact. In this review, we consider a number of key issues related to “gas biology,” including the effective tissue concentrations of these gases and the importance and significance of the physical proximity of gas-producing and gas-receptor/sensors. We also take an integrated approach to the interaction of gases by considering the physiological significance of CO, NO, and H2S on mitochondrial cytochrome c oxidase, a key target and central mediator of mitochondrial respiration. Additionally, we consider the effects of biologic gases on mitochondrial biogenesis and “suspended animation.” By evaluating gas-mediated control functions from both in vitro and in vivo perspectives, we hope to elaborate on the complex multiple interactions of O2, NO, CO, and H2S. Antioxid. Redox Signal. 13, 157–192. PMID:19939208

  2. U2 8 + -intensity record applying a H2 -gas stripper cell

    NASA Astrophysics Data System (ADS)

    Barth, Winfried; Adonin, Aleksey; Düllmann, Christoph E.; Heilmann, Manuel; Hollinger, Ralph; Jäger, Egon; Khuyagbaatar, Jadambaa; Krier, Joerg; Scharrer, Paul; Vormann, Hartmut; Yakushev, Alexander

    2015-04-01

    To meet the Facility for Antiproton and Ion Research science requirements higher beam intensity has to be achieved in the present GSI-accelerator complex. For this an advanced upgrade program for the UNILAC is ongoing. Stripping is a key technology for all heavy ion accelerators. For this an extensive research and development program was carried out to optimize for high brilliance heavy ion operation. After upgrade of the supersonic N2 -gas jet (2007), implementation of high current foil stripping (2011) and preliminary investigation of H2 -gas jet operation (2012), recently (2014) a new H2 -gas cell using a pulsed gas regime synchronized with arrival of the beam pulse has been developed. An obviously enhanced stripper gas density as well as a simultaneously reduced gas load for the pumping system result in an increased stripping efficiency, while the beam emittance remains the same. A new record intensity (7.8 emA) for 238U2 8 + beams at 1.4 MeV /u has been achieved applying the pulsed high density H2 stripper target to a high intensity 238U4 + beam from the VARIS ion source with a newly developed extraction system. The experimental results are presented in detail.

  3. H2O and HCl trace gas kinetics on crystalline HCl hydrates and amorphous HCl / H2O in the range 170 to 205 K: the HCl / H2O phase diagram revisited

    NASA Astrophysics Data System (ADS)

    Iannarelli, R.; Rossi, M. J.

    2014-05-01

    In this laboratory study, H2O ice films of 1 to 2 μm thickness have been used as surrogates for ice particles at atmospherically relevant conditions in a stirred flow reactor (SFR) to measure the kinetics of evaporation and condensation of HCl and H2O on crystalline and amorphous HCl hydrates. A multidiagnostic approach has been employed using Fourier transform infrared spectroscopy (FTIR) absorption in transmission to monitor the condensed phase and residual gas mass spectrometry (MS) for the gas phase. An average stoichiometric ratio of H2O : HCl = 5.8 ± 0.7 has been measured for HCl . 6H2O, and a mass balance ratio between HCl adsorbed onto ice and the quantity of HCl measured using FTIR absorption (Nin - Nesc - Nads) / NFTIR = 1.18 ± 0.12 has been obtained. The rate of evaporation Rev(HCl) for crystalline HCl hexahydrate (HCl . 6H2O) films and amorphous HCl / H2O mixtures has been found to be lower by a factor of 10 to 250 compared to Rev(H2O) in the overlapping temperature range 175 to 190 K. Variations of the accommodation coefficient α(HCl) on pure HCl . 6H2O up to a factor of 10 at nominally identical conditions have been observed. The kinetics (α, Rev) are thermochemically consistent with the corresponding equilibrium vapour pressure. In addition, we propose an extension of the HCl / H2O phase diagram of crystalline HCl . 6H2O based on the analysis of deconvoluted FTIR spectra of samples outside its known existence area. A brief evaluation of the atmospheric importance of both condensed phases - amorphous HCl / H2O and crystalline HCl . 6H2O - is performed in favour of the amorphous phase.

  4. Dynamic quantum molecular sieving separation of D2 from H2-D2 mixture with nanoporous materials.

    PubMed

    Niimura, Subaru; Fujimori, Toshihiko; Minami, Daiki; Hattori, Yoshiyuki; Abrams, Lloyd; Corbin, Dave; Hata, Kenji; Kaneko, Katsumi

    2012-11-14

    Quantum molecular sieving separability of D(2) from an H(2)-D(2) mixture was measured at 77 K for activated carbon fiber, carbon molecular sieve, zeolite and single wall carbon nanotube using a flow method. The amount of adsorbed D(2) was evidently larger than H(2) for all samples. The maximum adsorption ratio difference between D(2) and H(2) was 40% for zeolite (MS13X), yielding a selectivity for D(2) with respect to H(2) of 3.05.

  5. Lighting the Dark Molecular Gas Using the Mid Infrared H2 Rotational Lines

    NASA Astrophysics Data System (ADS)

    Togi, Aditya; Smith, JD

    2014-06-01

    The knowledge of molecular gas distribution is necessary to understand star formation in galaxies. The molecular gas content of galaxies must be inferred using indirect tracers since H2 which forms a major component of molecular gas in galaxies is not observable under typical conditions of interstellar medium. Physical processes causing enhancement and reduction of these tracers can cause misleading estimates of the molecular gas content in galaxies. We have devised a new method to measure molecular gas mass using quadrupole rotational lines of H2 found in the mid infrared spectra of various types of galaxies. We apply our model to derive the amount of molecular gas even in low metallicity galaxies where indirect tracers are unable to estimate the dark molecular gas mass. Bigiel, F., Leroy, A., Walter, F., et al. 2008, The Astronomical Journal, 136, 2846 (2008) Solomon, P. M., Rivolo, A. R., Barett, J., and Yahil, A. The Astrophysical Journal, 319, 730 (1987) Wolfire, M. G., Hollenbach, D., and McKee, C. F. The Astrophysical Journal, 716, 1191 (2010)

  6. Integrated vacuum absorption steam cycle gas separation

    DOEpatents

    Chen, Shiaguo [Champaign, IL; Lu, Yonggi [Urbana, IL; Rostam-Abadi, Massoud [Champaign, IL

    2011-11-22

    Methods and systems for separating a targeted gas from a gas stream emitted from a power plant. The gas stream is brought into contact with an absorption solution to preferentially absorb the targeted gas to be separated from the gas stream so that an absorbed gas is present within the absorption solution. This provides a gas-rich solution, which is introduced into a stripper. Low pressure exhaust steam from a low pressure steam turbine of the power plant is injected into the stripper with the gas-rich solution. The absorbed gas from the gas-rich solution is stripped in the stripper using the injected low pressure steam to provide a gas stream containing the targeted gas. The stripper is at or near vacuum. Water vapor in a gas stream from the stripper is condensed in a condenser operating at a pressure lower than the stripper to concentrate the targeted gas. Condensed water is separated from the concentrated targeted gas.

  7. Influence of Ar/O2/H2O Feed Gas and N2/O2/H2O Environment on the Interaction of Time Modulated MHz Atmospheric Pressure Plasma Jet (APPJ) with Model Polymers

    NASA Astrophysics Data System (ADS)

    Oehrlein, Gottlieb; Luan, Pingshan; Knoll, Andrew; Kondeti, Santosh; Bruggeman, Peter

    2016-09-01

    An Ar/O2/H2O fed time modulated MHz atmospheric pressure plasma jet (APPJ) in a sealed chamber was used to study plasma interaction with model polymers (polystyrene, poly-methyl methacrylate, etc.). The amount of H2O in the feed gas and/or present in the N2, O2, or N2/O2 environment was controlled. Short lived species such as O atoms and OH radicals play a crucial role in polymer etching and surface modifications (obtained from X-ray photoelectron spectroscopy of treated polymers without additional atmospheric exposure). Polymer etching depth for Ar/air fed APPJ mirrors the decay of gas phase O atoms with distance from the APPJ nozzle in air and is consistent with the estimated O atom flux at the polymer surface. Furthermore, whereas separate O2 or H2O admixture to Ar enhances polymer etching, simultaneous addition of O2 and H2O to Ar quenches polymer etching. This can be explained by the mutual quenching of O with OH, H and HO2 in the gas phase. Results where O2 and/or H2O in the environment were varied are consistent with these mechanisms. All results will be compared with measured and simulated species densities reported in the literature. We gratefully acknowledge funding from US Department of Energy (DE-SC0001939) and National Science Foundation (PHY-1415353).

  8. Anisotropic membranes for gas separation

    DOEpatents

    Gollan, Arye Z.

    1987-01-01

    A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7.degree.-25.degree. C. and then air dried at ambient temperature, typically 10.degree.-30.degree. C.

  9. Anisotropic membranes for gas separation

    DOEpatents

    Gollan, A.Z.

    1987-07-21

    A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7--25 C and then air dried at ambient temperature, typically 10--30 C. 2 figs.

  10. Highly sensitive hydrogen sulfide (H2 S) gas sensors from viral-templated nanocrystalline gold nanowires

    NASA Astrophysics Data System (ADS)

    Moon, Chung Hee; Zhang, Miluo; Myung, Nosang V.; Haberer, Elaine D.

    2014-04-01

    A facile, site-specific viral-templated assembly method was used to fabricate sensitive hydrogen sulfide (H2S) gas sensors at room temperature. A gold-binding M13 bacteriophage served to organize gold nanoparticles into linear arrays which were used as seeds for subsequent nanowire formation through electroless deposition. Nanowire widths and densities within the sensors were modified by electroless deposition time and phage concentration, respectively, to tune device resistance. Chemiresistive H2S gas sensors with superior room temperature sensing performance were produced with sensitivity of 654%/ppmv, theoretical lowest detection limit of 2 ppbv, and 70% recovery within 9 min for 0.025 ppmv. The role of the viral template and associated gold-binding peptide was elucidated by removing organics using a short O2 plasma treatment followed by an ethanol dip. The template and gold-binding peptide were crucial to electrical and sensor performance. Without surface organics, the resistance fell by several orders of magnitude, the sensitivity dropped by more than a factor of 100 to 6%/ppmv, the lower limit of detection increased, and no recovery was detected with dry air flow. Viral templates provide a novel, alternative fabrication route for highly sensitive, nanostructured H2S gas sensors.

  11. Passive gas separator and accumulator device

    DOEpatents

    Choe, H.; Fallas, T.T.

    1994-08-02

    A separation device employing a gas separation filter and swirler vanes for separating gas from a gas-liquid mixture is provided. The cylindrical filter utilizes the principle that surface tension in the pores of the filter prevents gas bubbles from passing through. As a result, the gas collects in the interior region of the filter and coalesces to form larger bubbles in the center of the device. The device is particularly suited for use in microgravity conditions since the swirlers induce a centrifugal force which causes liquid to move from the inner region of the filter, pass the pores, and flow through the outlet of the device while the entrained gas is trapped by the filter. The device includes a cylindrical gas storage screen which is enclosed by the cylindrical gas separation filter. The screen has pores that are larger than those of the filters. The screen prevents larger bubbles that have been formed from reaching and interfering with the pores of the gas separation filter. The device is initially filled with a gas other than that which is to be separated. This technique results in separation of the gas even before gas bubbles are present in the mixture. Initially filling the device with the dissimilar gas and preventing the gas from escaping before operation can be accomplished by sealing the dissimilar gas in the inner region of the separation device with a ruptured disc which can be ruptured when the device is activated for use. 3 figs.

  12. Powerful H2 Line Cooling in Stephan’s Quintet. II. Group-wide Gas and Shock Modeling of the Warm H2 and a Comparison with [C II] 157.7 μm Emission and Kinematics

    NASA Astrophysics Data System (ADS)

    Appleton, P. N.; Guillard, P.; Togi, A.; Alatalo, K.; Boulanger, F.; Cluver, M.; Pineau des Forêts, G.; Lisenfeld, U.; Ogle, P.; Xu, C. K.

    2017-02-01

    We map for the first time the two-dimensional H2 excitation of warm intergalactic gas in Stephan's Quintet on group-wide (50 × 35 kpc2) scales to quantify the temperature, mass, and warm H2 mass fraction as a function of position using Spitzer. Molecular gas temperatures are seen to rise (to T > 700 K) and the slope of the power-law density–temperature relation flattens along the main ridge of the filament, defining the region of maximum heating. We also performed MHD modeling of the excitation properties of the warm gas, to map the velocity structure and energy deposition rate of slow and fast molecular shocks. Slow magnetic shocks were required to explain the power radiated from the lowest-lying rotational states of H2, and strongly support the idea that energy cascades down to small scales and low velocities from the fast collision of NGC 7318b with group-wide gas. The highest levels of heating of the warm H2 are strongly correlated with the large-scale stirring of the medium as measured by [C ii] spectroscopy with Herschel. H2 is also seen associated with a separate bridge that extends toward the Seyfert nucleus in NGC 7319, from both Spitzer and CARMA CO observations. This opens up the possibility that both galaxy collisions and outflows from active galactic nuclei can turbulently heat gas on large scales in compact groups. The observations provide a laboratory for studying the effects of turbulent energy dissipation on group-wide scales, which may provide clues about the heating and cooling of gas at high z in early galaxy and protogalaxy formation.

  13. Passive gas separator and accumulator device

    DOEpatents

    Choe, Hwang; Fallas, Thomas T.

    1994-01-01

    A separation device employing a gas separation filter and swirler vanes for separating gas from a gasliquid mixture is provided. The cylindrical filter utilizes the principle that surface tension in the pores of the filter prevents gas bubbles from passing through. As a result, the gas collects in the interior region of the filter and coalesces to form larger bubbles in the center of the device. The device is particularly suited for use in microgravity conditions since the swirlers induce a centrifugal force which causes liquid to move from the inner region of the filter, pass the pores, and flow through the outlet of the device while the entrained gas is trapped by the filter. The device includes a cylindrical gas storage screen which is enclosed by the cylindrical gas separation filter. The screen has pores that are larger than those of the filters. The screen prevents larger bubbles that have been formed from reaching and interfering with the pores of the gas separation filter. The device is initially filled with a gas other than that which is to be separated. This technique results in separation of the gas even before gas bubbles are present in the mixture. Initially filling the device with the dissimilar gas and preventing the gas from escaping before operation can be accomplished by sealing the dissimilar gas in the inner region of the separation device with a ruptured disc which can be ruptured when the device is activated for use.

  14. Capillary transport of H2 gas generated locally in renal tissue.

    PubMed

    Kirkebø, A; Oien, A H; Aukland, K

    1983-01-01

    Previous measurements by microspheres have shown a higher blood flow in outer cortex and a lower blood flow in inner cortex than found by diffusible tracers. During vasodilation microspheres have indicated a disproportionate increase in deep cortical blood flow, whereas diffusible tracer distributions remained unchanged. These discrepancies could possibly be explained by a variable net inward transport of diffusible tracers in postglomerular vessels, the transport existing in control, but disappearing during vasodilation. To test this hypothesis H2 gas was produced electrolytically for 1 s at a platinum electrode in midcortex and the resulting gas concentration curve measured polarographically at two electrodes placed above and below the source. Analysis of a mathematical model showed that the ratio of the curve maxima at the two electrodes (Cmo/Cmi) would best reveal a radial net transport. Average Cmo/Cmi at 25 positions in 7 clamped dog kidneys was close to unity, but rose to 1.24 at control flow. During acetylcholine infusion Cmo/Cmi rose to 1.68. Local washout rates at the two electrodes increased equally. Calculations indicated a small outwardly directed net transport in control (3 X 10(-4) cm/s), becoming slightly reinforced during vasodilation (5 X 10(-4) cm/s). Thus the control transport direction is opposite to the hypothesis, and the change during vasodilation was estimated to be too small to explain the disparity between diffusible tracer uptake and microsphere distribution in control. H2 concentration maximum was obtained earlier under control flow than in the clamped kidney, indicating an increase in apparent D of the gas in tissue from 3 X 10(-5) cm2/s to 5 X 10(-5) cm2/s, probably due to mixing of H2 gas in the capillary net work.

  15. KOH post-etching-induced rough silicon nanowire array for H2 gas sensing application

    NASA Astrophysics Data System (ADS)

    Qin, Yuxiang; Wang, Yongyao; Liu, Yi; Zhang, Xiaojuan

    2016-11-01

    The limited surface area and compacted configuration of silicon nanowires (SiNWs), which are made by one-step metal-assisted chemical etching (MACE) go against target gas diffusion and adsorbtion for gas sensing application. To harvest suitable gas sensitivity and fast response-recovery characteristics, an aligned, rough SiNW array with loose configuration and high surface area was fabricated by a two-step etching process. The MACE technique was first employed to fabricate a smooth SiNW array, and then a KOH post-etching method was developed to roughen the NW surface further. The influence of the KOH post-etching time on the array density and surface roughness of the SiNWs was investigated, and the H2-sensing properties of the sensor based on the as-fabricated rough SiNW array were evaluated systematically at room temperature. It was revealed that the post-etching of KOH roughens the NW surface effectively, and also decreases the wire diameter and array density considerably. The resulting configuration of the SiNW array with high active surface and loose geometry is favorable for gas sensing. Consequently, the rough SiNW array-based sensor exhibited a linear response to H2 with a wide range of concentrations (50-10 000 ppm) at room temperature. Good stability and selectivity, satisfying response-recovery characteristics were also achieved. However, over-etching of SiNWs by KOH solution results in a considerable decrease in surface roughness and then in the H2-sensing response of the NWs.

  16. Ternary recombination of H3+, H2D+, HD2+, and D3+ with electrons in He/Ar/H2/D2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Kalosi, Abel; Dohnal, Petr; Plasil, Radek; Johnsen, Rainer; Glosik, Juraj

    2016-09-01

    The temperature dependence of the ternary recombination rate coefficients of H2D+ and HD2+ ions has been studied in the temperature range of 80-150 K at pressures from 500 to 1700 Pa in a stationary afterglow apparatus equipped with a cavity ring-down spectrometer. Neutral gas mixtures consisting of He/Ar/H2/D2 (with typical number densities 1017 /1014 /1014 /1014 cm-3) were employed to produce the desired ionic species and their fractional abundances were monitored as a function of helium pressure and the [D2]/[H2] ratio of the neutral gas. In addition, the translational and the rotational temperature and the ortho to para ratio were monitored for both H2D+ and HD2+ ions. A fairly strong pressure dependence of the effective recombination rate coefficient was observed for both ion species, leading to ternary recombination rate coefficients close to those previously found for (helium assisted) ternary recombination of H3+ and D3+. Work supported by: Czech Science Foundation projects GACR 14-14649P, GACR 15-15077S, GACR P209/12/0233, and by Charles University in Prague Project Nr. GAUK 692214.

  17. Theoretical calculations of pressure broadening coefficients for H2O perturbed by hydrogen or helium gas

    NASA Technical Reports Server (NTRS)

    Gamache, Robert R.; Pollack, James B.

    1995-01-01

    Halfwidths were calculated for H2O with H2 as a broadening gas and were estimated for He as the broadening species. The calculations used the model of Robert and Bonamy with parabolic trajectories and all relevant terms in the interaction potential. The calculations investigated the dependence of the halfwidth on the order of the atom-atom expansion, the rotational states, and the temperature in the range 200 to 400K. Finally, calculations were performed for many transitions of interest in the 5 micrometer window region of the spectrum. The resulting data will be supplied to Dr. R. Freedman for extracting accurate water mixing ratios from the analysis of the thermal channels for the Net Flux experiment on the Galileo probe.

  18. Possible microwave absorption by H2S gas in Uranus' and Neptune's atmospheres

    SciTech Connect

    De pater, Imke; Romani, P.N.; Atreya, S.K. Science Systems and Applications, Inc., Seabrook, MD Michigan, Univ., Ann Arbor )

    1991-06-01

    The disk-averaged brightness temperatures of the present 3.55 and 20.1 cm VLA observations are consistent with the planet's thermal spectra. It is estimated, on the basis of calculations which encompass microwave absorption by H2S, that the H2S mixing ratio on both Uranus and Neptune is probably enhanced by a factor of 10-30 above the elemental sulfur solar ratio. There is also more microwave opacity in the Neptune atmosphere than that of Uranus; this may be due to the presence of NH3 gas above the NH4SH cloud layer. Radio occultation data comparisons indicate the probability of NH3's supersaturation in the Neptune atmosphere. 42 refs.

  19. Hyperthin Organic Membranes for Gas Separations

    NASA Astrophysics Data System (ADS)

    Wang, Minghui

    selectivities, because a single PAA-glued LB bilayer made of a nonporous polymeric surfactant (ca. 7 nm) was found to exhibit a much higher H2/CO2 selectivity (200), which reached the "upper bound". The key factors that are likely to affect the quality of the glued LB bilayers were: (i) the degree of ionic crosslinking between surfactants and polyelectrolytes, (ii) charge repulsion and (iii) hydrogen bonding among the polyelectrolyte chains. In principle, employing a surfactant bearing a large number of ionic sites (e.g., a polymeric surfactant) that can increase the degree of ionic crosslinking and a weak polyelectrolyte (e.g., PAA) that can be optimized to minimize the charge repulsion and maximize the hydrogen bonding should afford glued LB films with high gas selectivities. The current finding also indicated that the PAA layer filled in between two surfactant monolayers served as the main gas barrier. In a related study, polyelectrolyte multilayers (PEMs) (ca. 14 nm in thickness), which were made from structurally matched (i.e., two oppositely charged polyelectrolytes having identical backbones) and unmatched polyelectrolytes pairs, both showed high CO2/N 2 selectivities (ca. 100-150). However, the permeabilities of PEMs derived from structurally matched polyelectrolytes were significantly higher than that from an unmatched pair. The larger solubility of CO 2 with respect to N2 in these PEMs should be the reason lead to the high CO2/N2 permeation selectivities.

  20. Recirculating gas separator for electric submersible

    SciTech Connect

    Powers, M.L.

    1991-01-01

    This patent describes a gas separator apparatus for a submersible well pump. It comprises: a rotary gas separator means; and recirculating means for recirculating a portion of the liquid discharged from the discharge outlet back to the separating chamber so that a gas-to-liquid ratio in the separator means is substantially lower than a gas-to-liquid ratio of well fluid entering the well fluid inlet wherein the recirculating means. This patent also describes a method of pumping liquid from a well producing well fluids having a relatively high gas-to-liquid ratio. It comprises: centrifugally separating the well fluid into a liquid and a gas with a separator located downhole in the well; directing the separated liquid toward an inlet of a submersible well pump; recycling a portion of the separated liquid to the separator; and providing an effective gas-to-liquid ratio in the separator substantially lower than a gas-to-liquid ratio of the well fluid prior to separation.

  1. Polyethylene/Potassium Titanate Separators For Ni/H2 Cells

    NASA Technical Reports Server (NTRS)

    Scott, William E.

    1995-01-01

    Experimental separators fabricated on paper-making machine. Two-layer, paperlike composite of polyethylene fibers and potassium titanate pigment shows promise for replacing asbestos as separator material in nickel/hydrogen electrochemical cells.

  2. Separation of H2S and NH3 gases from tofu waste water-based biogas using activated carbon adsorption

    NASA Astrophysics Data System (ADS)

    Harihastuti, Nani; Purwanto, P.; Istadi, I.

    2015-12-01

    Research on the separation of H2S and NH3 gases from tofu waste water-based biogas has been conducted to improve the content of CH4 of biogas in order to increase calorific value. Biogas from tofu waste water contained many kinds of gases such as: CH4 of 53-64%, CO2 of 36-45%, H2S of 3,724-5,880 mg/Nm3, NH3 of 0.19-70.36 mg/Nm3, and H2O of 33,800-19,770,000 mg/Nm3. In fact, CO2, H2S, NH3, and moisture are impurities that have disturbance to human and environment, so that they are necessary to be separated from biogas. Particularly, H2S and NH3 have high toxicity to people, particularly the workers in the tofu industry. Therefore, separation of H2S and NH3 from biogas to increase calorific value is the focus of this research. The method used in this research is by adsorption of H2S and NH3 gases using activated carbon as adsorbent. It also used condensation as pretreatment to remove moisture content in biogas. Biogas was flowed to adsorption column (70 cm height and 9 cm diameter containing activated carbon as much as 500 g) so that the H2S and NH3 gases were adsorbed. This research was conducted by varying flow rate and flow time of biogas. From this experiment, it was found that the optimum adsorption conditions were flow rate of 3.5 l/min and 4 hours flow time. This condition could reach 99.95% adsorption efficiency of H2S from 5,879.50 mg/Nm3 to 0.67 mg/Nm3, and 74.96% adsorption efficiency of NH3 from 2.93 mg/Nm3 to 0.73 mg/Nm3. The concentration of CH4 increased from 63.88% to 76.24% in the biogas.

  3. Hollow-Core Optical Fiber Gas Correlation Radiometer for CH4, H2CO, and H2O vapor measurements on Mars

    NASA Astrophysics Data System (ADS)

    Heaps, W. S.; Georgieva, E. M.; Wilson, E. L.

    2008-12-01

    We present the development of a reduced mass and volume gas correlation radiometer that implements a hollow-core fiber gas correlation cell. The reduction in size makes this technology appropriate for a Mars orbital or aircraft probe mission - capable of pin-pointing sources of atmospheric trace gases potentially indicative of life (methane, formaldehyde and water). The relative simplicity of this technique allows it to be easily expanded to include other species measurements such as 12C/13C ratios of methane. This instrument will consist of three sub-instruments for detecting CH4, H2CO, and H2O at 3.44 μm, 3.63 μm, and 3.12 μm respectively. Within each sub-instrument, a hollow-core optical fiber filled with a sample of the gas of interest acts as a spectral filter. Performance of a Mars orbiting version of the hollow-core fiber instrument has been simulated assuming a 2 meter long, 500 micron inner diameter hollow- core fiber gas correlation cell, a 92.8 degree sun-synchronous orbit from 400 km with a horizontal sampling scale of 10 km x 10 km. Initial results indicate that for one second of averaging, a detection limit of 1 ppbv is possible for formaldehyde, with slightly better than 1 ppbv. Preliminary results are presented for the formaldehyde sub-instrument development.

  4. Study of DC Circuit Breaker of H2-N2 Mixture Gas for High Voltage

    NASA Astrophysics Data System (ADS)

    Shiba, Yuji; Morishita, Yukinaga; Kaneko, Shuhei; Okabe, Shigemitsu; Mizoguchi, Hitoshi; Yanabu, Satoru

    Global warming caused by CO2 etc. is a field where the concern is very high. Especially, automobile emissions are problem for it. Therefore, the hybrid car is widely development and used recently. Hybrid car used electric power and gasoline. So, the car reduces CO2. Hybrid car has engine and motor. To rotate the motor, hybrid car has battery. This battery is large capacity. Therefore, the relay should interrupt high DC current for the switch of the motor and the engine. So, hybrid car used hydrogen gas filling relay We studied interruption test for the research of a basic characteristic of hydrogen gas. DC current has not current zero point. So, it is necessary to make the current zero by high arc voltage and forcible current zero point. The loss coefficient and arc voltage of hydrogen is high. Therefore, we studied interruption test for used high arc voltage. We studied interruption test and dielectric breakdown test of air, pure Hydrogen, and Hydrogen- nitrogen mixture gas. As a result, we realized H2-N2(80%-20%) is the best gas.

  5. Hot Gas in SMC SNR 0057-7226 and the Giant H 2 Region N66

    NASA Astrophysics Data System (ADS)

    Danforth, C. W.; Hoopes, C. G.; Sankrit, R.; Chu, Y.-H.; Sembach, K. R.; Blair, W. P.

    2001-12-01

    The supernova remnant SNR 0057-7226 and the dense, young cluster NGC 346 lie within the giant H 2 region N66, the most active star formation site in the SMC. Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the Wolf-Rayet binary system HD 5980, which lies behind the SNR, show high velocity, O 6 and C 3 absorption associated with the far side of the remnant (Hoopes et al 2001, ApJ, 558, L35). Chandra ACIS-I and ROSAT HRI images of N66 show the diffuse X-ray emission associated with the SNR, but little or no diffuse emission around the core of the central cluster. We present high-dispersion, long-slit optical echelle observations of five positions within N66 including positions across the SNR 0057-7226 and NGC 346. These data show bright Hα emission at the SMC rest velocity (v ~155 km s-1). Where the spectrograph slits intersect the SNR, faint Hα emission at high (v ~300 km s-1) and low (v ~50 km s-1) velocities reveals clumps of material on the back and front sides of the SNR shell. Ten FUSE observations of sight lines toward stars in N66--including four toward NGC 346 cluster stars--provide sensitive absorption-line measurements of several ionic species including O 6 which traces hot (T ~3*E5 K), highly-ionized gas and Fe 2 which traces cooler (T ~104 K), ionized and neutral gas. We also present ground based optical narrowband images in Hα , [S 2], and [O 3] which show the morphology of the H 2 region. We use this data set to study the kinematics of the gas in this complex region and to model the properties of the SNR-ISM interaction. This work is supported by NASA Contract NAS5-32985 to the Johns Hopkins University.

  6. The role of stabilised Criegee intermediate in gas phase H2SO4 formation

    NASA Astrophysics Data System (ADS)

    Novelli, A.; Hens, K.; Kubistin, D.; Tatum Ernest, C.; Trawny, K.; Rudolf, M.; Auld, J.; Axinte, R.; Hosaynali Beygi, Z.; Nölscher, A.; Paasonen, P.; Sipilä, M.; Keronen, P.; Petdjd, T. T.; Adame, J.; Elste, T.; Werner, A.; Englert, J.; Plass-Duelmer, C.; Fischer, H.; Williams, J.; Vereecken, L.; Martinez, M.; Lelieveld, J.; Harder, H. D.

    2012-12-01

    Sulfuric acid in the gas phase plays a central role in new particle formation and in particle growth. Fine particles directly affect human health via inhalation and have an important impact on climate. In the gas phase, sulfuric acid is known to be formed from the oxidation of SO2 by the OH radical in the presence of oxygen and water. In the last decade, new measurements of OH and H2SO4 have shown relatively high concentrations of H2SO4 during nighttime when the corresponding concentration of OH radicals was too low to explain such high concentrations of sulfuric acid. New laboratory experiments, in addition to theoretical studies, have shown that a possible candidate for the oxidation of SO2 is Stabilized Criegee Intermediates (SCIs) arising from the ozonolysis of alkenes. The rate coefficient for the reaction of CH2OO + SO2 has been measured at 3.9 x 10-11 cm3 molecule-1 s-1 indicating a probable competing role for the SCI in the production of sulfuric acid. Measurements of a fraction of atmospheric SCIs with laser-induced fluorescence (LIF) have been made using a chemical subtraction method both in the laboratory and in the field. The SCIs undergo unimolecular decomposition at low pressure inside the instrument forming OH that is then detected. Model results and laboratory tests confirm our findings. This new instrumental setup has been used in several environments including Finland (HUMPPA-COPEC), Spain (DOMINO HOx) and Germany (HOPE 2012) revealing a unique SCI signal strongly influenced by different kinds of vegetation and meteorological conditions. Results from the HUMPPA campaign show a missing H2SO4 production after taking into account the contribution of the OH radical. The SCIs signal measured with our instrument shows a good correlation with this missing production confirming the important role of the SCI in the oxidation of SO2 and in the formation of sulfuric acid. Using the missing H2SO4 production rate together with the rate coefficient for the

  7. New Gas Carburizing Method for Minimizing CO2 Emission by Saving Resources and Selective Removal of H2 in Furnace

    NASA Astrophysics Data System (ADS)

    Mizukoshi, Tomoyuki; Yokoyama, Yujiro; Hoshino, Hideaki; Ishigami, Itsuo; Usui, Tateo

    An attempt has been made to develop a new gas carburizing furnace with the system that discharges H2 gas selectively from the atmosphere in the furnace. Polyimide hollow-fiber membrane filter on the market was selected as a filter that was expected to have good H2 gas permeability and selectivity. The results of the various gas permeability measurements of this filter showed that it had superior H2 gas permeability and selectivity. Using this gas filter module, a new industrial gas carburizing furnace that had ‘H2 gas selective discharging system’ was produced as a trial. Use of this furnace made possible to stabilize the gas carburizing atmosphere in the furnace under the lower carrier gas flow rate condition (below 25% of standard condition). It was confirmed that the carbon concentration profile of the steel carburized with the new carburizing furnace under lower carrier gas flow rate condition was comparable to that of the specimen carburized under standard carrier gas flow rate condition.

  8. On the 1A1 - 3B1 separation in CH2 and SiH2

    NASA Astrophysics Data System (ADS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1987-07-01

    The 1A1 - 3B1 separation in CH2 and SiH2 has been computed using extended basis sets and CASSCF/SOCI wave functions. Using theoretical estimates for the effects of zero-point vibration yields T(0) values of 8.9 and -20.9 kcal/mol respectively, in excellent agreement with the experimental values of 9.02 and -21.0 kcal/mol. A corollary to the small zero-point vibrational contribution to the separation is that the symmetric stretching fundamental in CH2(3B1) must be near 3100/cm, much less than a recently suggested value of around 3400/cm. An accurate Te value for SiH2 establishes the ionization potential of the 1A1 state as 9.15 eV, the higher of two recent experimental values.

  9. Mars Atmospheric Capture and Gas Separation

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony; Santiago-Maldonado, Edgardo; Gibson, Tracy; Devor, Robert; Captain, James

    2011-01-01

    The Mars atmospheric capture and gas separation project is selecting, developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Trace gases will be required to be separated from Martian atmospheric gases to provide pure C02 to processing elements. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and should be captured as welL To achieve these goals, highly efficient gas separation processes will be required. These gas separation techniques are also required across various areas within the ISRU project to support various consumable production processes. The development of innovative gas separation techniques will evaluate the current state-of-the-art for the gas separation required, with the objective to demonstrate and develop light-weight, low-power methods for gas separation. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from un-reacted carbon oxides (C02- CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, (3) carbon oxides from oxygen from a trash/waste processing reaction, and (4) helium from hydrogen or oxygen from a propellant scavenging process. Potential technologies for the separations include freezers, selective membranes, selective solvents, polymeric sorbents, zeolites, and new technologies. This paper and presentation will summarize the results of an extensive literature review and laboratory evaluations of candidate technologies for the capture and separation of C02 and other relevant gases.

  10. Separation of H(2)SO(4) + CuSO(4) mixture by diffusion dialysis.

    PubMed

    Palatý, Z; Záková, A

    2004-10-18

    Diffusion dialysis of aqueous solution of H(2)SO(4) + CuSO(4) has been investigated in a two-compartment cell with an anion-exchange membrane Neosepta-AFN. The experiments have proved that sulfuric acid permeates well through the membrane used, while cupric sulfate is efficiently rejected. This operation is very effective at high acid concentrations and low concentrations of cupric sulfate. Furthermore, it has been found that even at the highest concentration of CuSO(4), the rejection coefficient is higher than 0.965. The flux of CuSO(4) calculated from the time dependences of the CuSO(4) concentration is negatively influenced by increasing acid concentration.

  11. Gas separation performance of inorganic polyphosphazene membranes

    SciTech Connect

    Stone, M.L.

    1995-07-01

    The objective of this research program was to develop, characterize, and evaluate the potential of phosphazene polymers for separations performed in harsh environments. The program was divided into two general areas, gas separations and metal ion separations involving aqueous solutions. Each of these two areas is the subject of a topical report; this report deals with the gas separations. Throughout the world, there is rapidly growing interest in membrane separation as an energy efficient way to separate components of a process stream or waste stream, such as in desalination of water or clarification of fruit juices. In some cases membranes perform separations that are otherwise very difficult, such as breaking azeotropes. In the early stages of the work reported here, there was interest in separating acid gases from process flue gases and in natural gas sweetening. As a result, research was undertaken to characterize membrane performance. First, a pure gas test apparatus was developed to determine the permeabilities of a number of gases through various membranes at a variety of temperatures. Second, an automated mixed gas test cell was developed in which membranes could be exposed to mixtures of pairs of gases. Each of these approaches has its advantages and each will be discussed separately.

  12. Efficient Light-driven Long Distance Charge Separation and H2 Generation in Semiconductor Quantum Rods and Nanoplatelets

    NASA Astrophysics Data System (ADS)

    Lian, Tianquan

    Quantum confined semiconductor nanocrystals (0D quantum dots, 1D quantum rods and 2D quantum platlets) have been intensively investigated as light harvesting and charge separation materials for photovoltaic and photocatalytic applications. The efficiency of these semiconductor nanocrystal-based devices depends on many fundamental processes, including light harvesting, carrier relaxation, exciton localization and transport, charge separation and charge recombination. The competition between these processes determines the overall solar energy conversion (solar to electricity or fuel) efficiency. Semiconductor nano-heterostructures, combining two or more material components, offer unique opportunities to control their charge separation properties by tailoring their compositions, dimensions and spatial arrangement. Further integration of catalysts (heterogeneous or homogeneous) to these materials form multifunctional nano-heterostructures. Using 0D, 1D and 2D CdSe/CdS/Pt heterostructures as model systems, we directly probe the above-mentioned fundamental exciton and carrier processes by transient absorption and time-resolved fluorescence spectroscopy. We are examining how to control these fundamental processes through the design of heterostructures to achieve long-lived charge separation and efficient H2 generation. In this talk, we will discuss a new model for exciton dissociation by charge transfer in quantum dots (i.e. Auger assisted electron transfer), mechanism of 1D and 2D exciton transport and dissociation in nanorods, and key factors limiting H2 generation efficiency in CdSe/CdS/Pt nanorod heterostructures.

  13. Sequential hydration energies of the sulfate ion, from determinations of the equilibrium constants for the gas-phase reactions: SO4(H2O)(n)2- = SO4(H2O)(n-1)2- + H2O.

    PubMed

    Blades, Arthur T; Kebarle, Paul

    2005-09-22

    Sequential hydration energies of SO4(H2O)(n)2- were obtained from determinations of the equilibrium constants of the following reactions: SO4(H2O)(n)2- = SO4(H2O)(n-1)2- + H2O. The SO4(2-) ions were produced by electrospray and the equilibrium constants Kn,n-1 were determined with a reaction chamber attached to a mass spectrometer. Determinations of Kn,n-1 at different temperatures were used to obtain DeltaG0n,n-1, DeltaH0 n,n-1, and DeltaS0n,n-1 for n = 7 to 19. Interference of the charge separation reaction SO4(H2O)(n)2- = HSO4(H2O)(n-k)- + OH(H2O)(k-1)- at higher temperatures prevented determinations for n < 7. The DeltaS0n,n-1 values obtained are unusually low and this indicates very loose, disordered structures for the n > or = 7 hydrates. The DeltaH0n,n-1 values are compared with theoretical values DeltaEn,n-1, obtained by Wang, Nicholas, and Wang. Rate constant determinations of the dissociation reactions n,n - 1, obtained with the BIRD method by Wong and Williams, showed relatively lower rates for n = 6 and 12, which indicate that these hydrates are more stable. No discontinuities of the DeltaG0n,n-1 values indicating an unusually stable n = 12 hydrate were observed in the present work. Rate constants evaluated from the DeltaG0n,n-1 results also fail to indicate a lower rate for n = 12. An analysis of the conditions used in the two types of experiments indicates that the different results reflect the different energy distributions expected at the dissociation threshold. Higher internal energies prevail in the equilibrium measurements and allow the participation of more disordered transition states in the reaction.

  14. Radioactive-gas separation technique

    NASA Technical Reports Server (NTRS)

    Haney, R.; King, K. J.; Nellis, D. O.; Nisson, R. S.; Robling, P.; Womack, W.

    1977-01-01

    Cryogenic technique recovers gases inexpensively. Method uses differences in vapor pressures, melting points, and boiling points of components in gaseous mixture. Series of temperature and pressure variations converts gases independently to solid and liquid states, thereby simplifying separation. Apparatus uses readily available cryogen and does not require expensive refrigeration equipment.

  15. Simulation of Ultrasonic-driven Gas Separations

    SciTech Connect

    Rector, David R.; Greenwood, Margaret S.; Ahmed, Salahuddin; Doctor, Steven R.; Posakony, Gerald J.; Stenkamp, Victoria S.

    2007-06-01

    The separation of components in a gas mixture is important for a wide range of applications. One method for achieving this separation is by passing a traveling acoustic wave through the gas mixture, which creates a flux of the lighter components away from the transducer. A series of simulation were performed to assess the effectiveness of this method for separating a binary mixture of argon and helium using the lattice kinetics method. The energy transport equation was modified to account for adiabatic expansion and compression. The species transport equation was modified to include a barodiffusion term. Simulations were performed on two different scales; detailed acoustic wave simulations to determine the net component flux as a function of local concentration, pressure, etc., and device scale simulations to predict the gas composition as a function of time inside a gas separation cylinder. The method is first validated using data from literature and then applied to mixtures of argon and helium. Results are presented and discussed.

  16. Method for improved gas-solids separation

    DOEpatents

    Kusik, Charles L.; He, Bo X.

    1990-01-01

    Methods are disclosed for the removal of particulate solids from a gas stream at high separation efficiency, including the removal of submicron size particles. The apparatus includes a cyclone separator type of device which contains an axially mounted perforated cylindrical hollow rotor. The rotor is rotated at high velocity in the same direction as the flow of an input particle-laden gas stream to thereby cause enhanced separation of particulate matter from the gas stream in the cylindrical annular space between the rotor and the sidewall of the cyclone vessel. Substantially particle-free gas passes through the perforated surface of the spinning rotor and into the hollow rotor, from when it is discharged out of the top of the apparatus. Separated particulates are removed from the bottom of the vessel.

  17. Method for improved gas-solids separation

    DOEpatents

    Kusik, C.L.; He, B.X.

    1990-11-13

    Methods are disclosed for the removal of particulate solids from a gas stream at high separation efficiency, including the removal of submicron size particles. The apparatus includes a cyclone separator type of device which contains an axially mounted perforated cylindrical hollow rotor. The rotor is rotated at high velocity in the same direction as the flow of an input particle-laden gas stream to thereby cause enhanced separation of particulate matter from the gas stream in the cylindrical annular space between the rotor and the sidewall of the cyclone vessel. Substantially particle-free gas passes through the perforated surface of the spinning rotor and into the hollow rotor, from where it is discharged out of the top of the apparatus. Separated particulates are removed from the bottom of the vessel. 4 figs.

  18. Sulfidation Kinetics of Natural Chromite Ore Using H2S Gas

    NASA Astrophysics Data System (ADS)

    Ahmad, Sazzad; Rhamdhani, M. Akbar; Pownceby, Mark I.; Bruckard, Warren J.

    2015-04-01

    The kinetics and mechanism of natural chromite (FeCr2O4) sulfidation using 5 pct H2S (balance Ar) gas were studied in the temperature range 1173 K to 1473 K (900 °C to 1200 °C). Reaction products were examined using combined X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Results indicated the formation of an outer sulfide-rich layer comprising mixed (Fe,Cr)1- x S and (Cr,Fe)1- x S phases, underlain by a cation-depleted diffusion zone. The kinetics investigation indicated that the reaction rate increased with increasing temperature and that the sulfidation of chromite followed a shrinking unreacted core model. It is proposed that Cr3+ cation diffusion through the reaction product was the rate controlling step with an apparent activation energy of 166 ± 4 kJ mol-1. The calculated activation energy lies between the activation energy for Fe2+ and Cr3+ diffusion through pure chromite spinel and Fe-Cr alloy. Possible reasons for the discrepancy from pure chromite are expected to be the presence of minor Al and Mg in the natural chromite sample, and the partial pressure of oxygen under the reaction conditions used.

  19. Oxidation and Condensation of Zinc Fume From Zn-CO2-CO-H2O Streams Relevant to Steelmaking Off-Gas Systems

    NASA Astrophysics Data System (ADS)

    Bronson, Tyler M.; Ma, Naiyang; Zhu, Liang Zhu; Sohn, Hong Yong

    2017-01-01

    The objective of this research was to study the condensation of zinc vapor to metallic zinc and zinc oxide solid under varying environments to investigate the feasibility of in-process separation of zinc from steelmaking off-gas dusts. Water vapor content, temperature, degree of cooling, gas composition, and initial zinc partial pressure were varied to simulate the possible conditions that can occur within steelmaking off-gas systems, limited to Zn-CO2-CO-H2O gas compositions. The temperature of deposition and the effect of rapidly quenching the gas were specifically studied. A homogeneous nucleation model for applicable experiments was applied to the analysis of the experimental data. It was determined that under the experimental conditions, oxidation of zinc vapor by H2O or CO2 does not occur above 1108 K (835 °C) even for highly oxidizing streams (CO2/CO = 40/7). Rate expressions that correlate CO2 and H2O oxidation rates to gas composition, partial pressure of water vapor, temperature, and zinc partial pressure were determined to be as follows: Rate ( mol/m2s ) = 406 exp ( -50.2 kJ/mol/RT ) ( p_{Zn} p_{CO}2 - p_{CO} /K_{eq}, CO2 ) mol/m2 × s Rate ( mol/m2 s ) = 32.9 exp ( -13.7 kJ/mol/RT ) ( p_{Zn} p_{H}2 O - p_{H}2 /K_{eq}, H2 O ) mol/m2 × s It was proven that a rapid cooling rate (500 K/s) significantly increases the ratio of metallic zinc to zinc oxide as opposed to a slow cooling rate (250 K/s). SEM analysis found evidence of heterogeneous growth of ZnO as well as of homogeneous formation of metallic zinc. The homogeneous nucleation model fit well with experiments where only metallic zinc deposited. An expanded model with rates of oxidation by CO2 and H2O as shown was combined with the homogenous nucleation model and then compared with experimental data. The calculated results based on the model gave a reasonable fit to the measured data. For the conditions used in this study, the rate equations for the oxidation of zinc by carbon dioxide and water vapor

  20. Oxidation and Condensation of Zinc Fume From Zn-CO2-CO-H2O Streams Relevant to Steelmaking Off-Gas Systems

    NASA Astrophysics Data System (ADS)

    Bronson, Tyler M.; Ma, Naiyang; Zhu, Liang Zhu; Sohn, Hong Yong

    2017-04-01

    The objective of this research was to study the condensation of zinc vapor to metallic zinc and zinc oxide solid under varying environments to investigate the feasibility of in-process separation of zinc from steelmaking off-gas dusts. Water vapor content, temperature, degree of cooling, gas composition, and initial zinc partial pressure were varied to simulate the possible conditions that can occur within steelmaking off-gas systems, limited to Zn-CO2-CO-H2O gas compositions. The temperature of deposition and the effect of rapidly quenching the gas were specifically studied. A homogeneous nucleation model for applicable experiments was applied to the analysis of the experimental data. It was determined that under the experimental conditions, oxidation of zinc vapor by H2O or CO2 does not occur above 1108 K (835 °C) even for highly oxidizing streams (CO2/CO = 40/7). Rate expressions that correlate CO2 and H2O oxidation rates to gas composition, partial pressure of water vapor, temperature, and zinc partial pressure were determined to be as follows: Rate( mol/m2 s ) = 406 \\exp ( - 50.2 kJ/mol/RT )( p_Zn p_{CO2 - p_CO /K_{eq,CO2 ) mol/m2 × s Rate( mol/m2 s ) = 32.9 \\exp ( - 13.7 kJ/mol/RT )( p_Zn p_{H2 O - p_{H2 /K_{eq,H2 O ) mol/m2 × s It was proven that a rapid cooling rate (500 K/s) significantly increases the ratio of metallic zinc to zinc oxide as opposed to a slow cooling rate (250 K/s). SEM analysis found evidence of heterogeneous growth of ZnO as well as of homogeneous formation of metallic zinc. The homogeneous nucleation model fit well with experiments where only metallic zinc deposited. An expanded model with rates of oxidation by CO2 and H2O as shown was combined with the homogenous nucleation model and then compared with experimental data. The calculated results based on the model gave a reasonable fit to the measured data. For the conditions used in this study, the rate equations for the oxidation of zinc by carbon dioxide and water vapor as well

  1. Measurement of dissolved H2, O2, and CO2 in groundwater using passive samplers for gas chromatographic analyses.

    PubMed

    Spalding, B P; Watson, D B

    2006-12-15

    A simple in-situ passive dissolved gas groundwater sampler, comprised of a short length of silicone tubing attached to a gastight or other syringe, was adapted and tested for in-situ collection of equilibrium gas samples. Sampler retrieval after several days of immersion in groundwater allowed the direct injection of the sample onto a gas chromatograph (GC), simplifying field collection and sample handling over the commonly used "bubble stripping" method for H2 analyses. A GC was modified by sequencing a thermal conductivity (TC) detector followed by a reductive gas (RG) detector so that linear calibration of H2 over the range 0.2-200,000 ppmv was attained using a 0.5-mL gas sample; inclusion of the TC detector allowed the simultaneous quantification of other fixed gases (O2, CO2, He, and Ne) to which the RG detector was not responsive. Uptake kinetics for H2 and He indicated that the passive sampler reached equilibrium within 12 h of immersion in water. Field testing of these passive samplers revealed unusually large equilibrium gas-phase H2 concentrations in groundwater, ranging from 0.1 to 13.9%, by volume, in 11 monitoring wells surrounding four former radiological wastewater disposal ponds at the Y-12 plant in Oak Ridge, Tennessee.

  2. Regenerative adsorption and removal of H2S from hot fuel gas streams by rare earth oxides.

    PubMed

    Flytzani-Stephanopoulos, Maria; Sakbodin, Mann; Wang, Zheng

    2006-06-09

    Sorbent materials that allow for high-temperature, regenerative desulfurization of fuel gas streams for the anode of a solid oxide fuel cell have been developed. Reversible adsorption of H2S on cerium and lanthanum oxide surfaces is demonstrated over many cycles at temperatures as high as 800 degrees C, on both fresh or presulfided sorbents, and at very high space velocities. The adsorption and desorption processes are very fast, and removal of H2S to sub-parts per million levels is achieved at very short (millisecond) contact times. Any type of sulfur-free gas, including water vapor, can be used to regenerate the sorbent surface. Preferably, the anode off-gas stream is used to sweep the desorbed H(2)S to a burner.

  3. The fabrication of high sensitivity gold nanorod H2S gas sensors utilizing the highly uniform anodic aluminum oxide template

    NASA Astrophysics Data System (ADS)

    Li, Chien-Yu; Li, Ciao-Yu; Wu, You-Lin; Hsu, Chung-Ping; Lee, Ming-Ching; Houng, Mau-Phon

    2016-12-01

    Gold nanorod were fabricated using anodic alumina oxide template for H2S gas detection. The nanorod gas sensor exhibits high surface density and contact area, which can increase detection sensitivity. The anodic alumina oxide template contains an array of pores, with a width of 70 nm and a length of 27 μ m . Au nanorod were obtained through electro-deposition under a pulse bias of -1 V. The resistance of the Au nanorod was recorded upon exposure to various concentrations of H2S. The resistance could be attributed to the high electron affinity between sulfide and Au nanorod. Au-sulfide bonds provide strong bonding, which could alter the conductivity of the sensor. The gas sensor exhibits high sensitivity and short response time for H2S detection at room temperature.

  4. Binary rototranslational hyper-Rayleigh spectra of H(2)-He gas mixture.

    PubMed

    Godet, J-L; Bancewicz, T; Głaz, W; Maroulis, G; Haskopoulos, A

    2009-11-28

    The collision-induced rototranslational hyper-Rayleigh spectra of gaseous H(2)-He mixture are computed and discussed in the binary regime. As the input data we use our ab initio computed H(2)-He collision-induced first dipole hyperpolarizability tensor Deltabeta(R). Both the vector and the septor part of the H(2)-He hyper-Rayleigh spectra are evaluated at room temperature (T=295 K). The spectra are calculated assuming the full quantum computations based on the Schrödinger equation of the relative translational motion in the isotropic H(2)-He potential as well as using semiclassical methods.

  5. Gas Strut Separation Alternative for Ares I

    NASA Technical Reports Server (NTRS)

    Floyd, Brian; Owens, James

    2008-01-01

    This paper presents a design alternative and the rationale for a stage separation system based on Metering Adiabatic Gas Struts (MAG Struts) for the Ares 1 launch vehicle. The MAG Strut separation system was proposed as an alternative to the current Ares 1 separation system, which relies on small solid rocket motors to provide the main separation force. This paper will describe technical issues that were addressed during the trade study and present a conceptual design of the strut system that best resolved the issues. Needed development testing and programmatic considerations will be addressed as part of the paper.

  6. Micro-structural optimization of polybenzimidazole-based membranes for H2/CO2 separation at elevated temperatures

    SciTech Connect

    Singh, Rajinder P; Li, Xin; Dudeck, Kevin W; Benicewicz, Brian C; Berchtold, Kathryn A

    2012-06-12

    There is compelling need to develop novel separation methods to improve the energy efficiency of synthesis (syn) gas processing operations including H{sub 2} and H{sub 2}/CO production to meet power, chemicals, and fuel producer needs, as well as carbon capture and removal of other undesirable syngas impurities. To be technically and economically viable, a successful separation method must be applicable to industrially relevant gas streams at realistic process conditions and compatible with large gas volumes. H{sub 2} selective membrane technology is a promising method for syngas separations at elevated temperatures (>150 C) that could be positioned upstream or downstream of one or more of the water-gas-shift reactors (WGSRs) or integrated with a WGSR depending on application specific syngas processing. Polybenzimidazole (PBI)-based polymer chemistries are exceptional candidates for H{sub 2}/CO{sub 2} separations at elevated temperatures. In general, these materials possess excellent chemical resistance, very high glass transition temperatures (> 400 C), good mechanical properties, and an appropriate level of processability. Although commercially available PBI polymers have demonstrated commercially attractive H{sub 2}/CO{sub 2} selectivity, their H{sub 2} permeability is low. Our team s employing structural and chemical manipulations to tailor the polymer free-volume achitecture with the ultimate goal of enhancing H{sub 2} permselectivity while retaining the inherent hermochemical stability characteristics of PBI. We will discuss our synthetic approaches and their influences on the gas transport behavior of these PBI-based materials. In general, a decrease in H{sub 2}/CO{sub 2} selectivity was observed with an increase in H{sub 2} permeability. H{sub 2} permeability and H{sub 2}/CO{sub 2} selectivity at 250 C ranged from 50 to 1000 barrer and 5 to 45, respectively.

  7. Collision-induced hyper-Rayleigh spectrum of H(2)-Ar gas mixture.

    PubMed

    Bancewicz, Tadeusz; Głaz, Waldemar; Godet, Jean-Luc; Maroulis, George

    2008-09-28

    The collision-induced hyper-Rayleigh (CIHR) spectra of the gaseous H(2)-Ar mixture are discussed in the binary regime on the basis of our ab initio computed H(2)-Ar collision-induced (CI) first dipole hyperpolarizability tensor Deltabeta(R). A method for the computation of the spherical, rotationally adapted components Deltabeta(lambdaL) ((s,K))(R) of Deltabeta(R) needed for spectroscopic line shape analysis is proposed. Both the vector and the septor parts of the H(2)-Ar CIHR spectrum are evaluated at room (T=295 K) temperature. The spectra are calculated assuming the full quantum computations based on the Schrodinger equation of the relative translational motion of H(2)-Ar as well as semiclassical methods (classical trajectory approach and Birnbaum-Cohen model translational profiles). The H(2)-Ar pair CIHR septor spectrum has been found stronger than the vector one.

  8. Separation of gas mixtures by supported complexes

    SciTech Connect

    Nelson, D.A.; Lilga, M.A.; Hallen, R.T.; Lyke, S.E.

    1986-08-01

    The goal of this program is to determine the feasibility of solvent-dissolved coordination complexes for the separation of gas mixtures under bench-scale conditions. In particular, mixtures such as low-Btu gas are examined for CO and H/sub 2/ separation. Two complexes, Pd/sub 2/(dpm)/sub 2/Br/sub 2/ and Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, were examined in a bench-scale apparatus for the separation of binary (CO-N/sub 2/ or H/sub 2/-N/sub 2/) and quinary (H/sub 2/, CO, CO/sub 2/, CH/sub 4/, and N/sub 2/) mixtures. The separation of CO-N/sub 2/ was enhanced by the presence of the palladium complex in the 1,1,2-trichloroethane (TCE) solvent, especially at high gas and low liquid rates. The five-component gas mixture separation with the palladium complex in TCE provided quite unexpected results based on physical solubility and chemical coordination. The complex retained CO, while the solvent retained CO/sub 2/, CH/sub 4/, and N/sub 2/ to varying degrees. This allowed the hydrogen content to be enhanced due to its low solubility in TCE and inertness to the complex. Thus, a one-step, hydrogen separation can be achieved from gas mixtures with compositions similar to that of oxygen-blown coal gas. A preliminary economic evaluation of hydrogen separation was made for a system based on the palladium complex. The palladium system has a separation cost of 50 to 60 cents/MSCF with an assumed capital investment of $1.60/MSCF of annual capacity charged at 30% per year. This assumes a 3 to 4 year life for the complex. Starting with a 90% hydrogen feed, PSA separation costs are in the range of 30 to 50 cents/MSCF. The ruthenium complex was not as successful for hydrogen or carbon monoxide separation due to unfavorable kinetics. The palladium complex was found to strip hydrogen gas from H/sub 2/S. The complex could be regenerated with mild oxidants which removed the sulfur as SO/sub 2/. 24 refs., 26 figs., 10 tabs.

  9. UPGRADING NATURAL GAS VIA MEMBRANE SEPARATION PROCESSES

    SciTech Connect

    S.A.Stern; P.A. Rice; J. Hao

    2000-03-01

    The objective of the present study is to assess the potential usefulness of membrane separation processes for removing CO{sub 2} and H{sub 2}S from low-quality natural gas containing substantial amounts of both these ''acid'' gases, e.g., up to 40 mole-% CO{sub 2} and 10 mole-% H{sub 2}S. The membrane processes must be capable of upgrading the crude natural gas to pipeline specifications ({le} 2 mole-% CO{sub 2}, {le} 4 ppm H{sub 2}S). Moreover, these processes must also be economically competitive with the conventional separation techniques, such as gas absorption, utilized for this purpose by the gas industry.

  10. Monitoring of CO2/H2S gas mixture injection in basaltic rocks at Hellisheiði Geothermal Power Plant, Iceland

    NASA Astrophysics Data System (ADS)

    Clark, Deirdre E.; Gunnarsson, Ingvi; Aradóttir, Edda S.; Gunnlaugsson, Einar; Júlíusson, Bjarni M.; Matter, Juerg M.; Stute, Martin; Oelkers, Eric H.; Snæbjörnsdóttir, Sandra Ó.; Gíslason, Sigurður R.

    2016-04-01

    Hellisheiði geothermal power plant emits about 41,000 tonnes of CO2 and 10,000 tonnes of H2S per year as a by-product of geothermal energy production. Icelandic regulations, stricter than WHO guidelines, have been in effect in order to reduce H2S emissions of the geothermal industry, while carbon capture and storage (CCS) is one method recommended to minimise the amount of CO2 released into the atmosphere. The overall cost of CCS is dominated by that of capture and gas separation. This capture cost could be lowered by injecting gas mixtures into rocks as is now being tested at Hellisheiði geothermal power plant in SW-Iceland. There, a gas mixture of 60% CO2 and 40% H2S is dissolved in water from the plant and injected into the basaltic rocks. The CarbFix and SulFix pilot projects demonstrated solubility storage of the pure separate gases in a few minutes [1,2] and that more than 80% of the injected CO2 into basaltic rocks was mineralised within a year from its injection at 20-50°C [3]. The first phase of the gas mixture injection began on 3 June 2014, while tracer tests started three weeks later. By the end of the year 2015, approximately 6280 tonnes of CO2 and 3520 tonnes of H2S had been injected. The gases are dissolved in condensation water, mixed with waste water and injected to 750 m depth into a high temperature reservoir of 200-270°C. Water and gas samples were collected from four monitoring wells. There is a minor increase in CO2 (total dissolved carbon) and H2S (total dissolved sulphite), while the majority of major and minor elements are relatively stable. The data from monitoring wells therefore suggests that some of the injected gas mixture is already stored as minerals in the basaltic reservoir. [1] Sigfusson et al. (2015) Int. J. of Greenh. Gas Control 37, 213-219. [2] Gunnarsson et al. (2013) GRC Transactions 37, 785-789. [3] Matter et al. (2014) Energy Procedia 63, 4180-4185.

  11. Crosslinked Polybenzimidazole Membrane For Gas Separation

    SciTech Connect

    Jorgensen, Betty S.; Young, Jennifer S.; Espinoza, Brent F.

    2005-09-20

    A cross-linked, supported polybenzimidazole membrane for gas separation is prepared by layering a solution of polybenzimidazole (PBI) and a,a'dibromo-p-xylene onto a porous support and evaporating solvent. A supported membrane of cross-linked poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole unexpectedly exhibits an enhanced gas permeability compared to the non-cross linked analog at temperatures over 265° C.

  12. 30 CFR 250.1164 - What are the requirements for flaring or venting gas containing H2S?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 2 2011-07-01 2011-07-01 false What are the requirements for flaring or venting gas containing H2S? 250.1164 Section 250.1164 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT....1163, and the following additional requirements: (1) For safety or air pollution prevention...

  13. 30 CFR 250.1164 - What are the requirements for flaring or venting gas containing H2S?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 2 2014-07-01 2014-07-01 false What are the requirements for flaring or venting gas containing H2S? 250.1164 Section 250.1164 Mineral Resources BUREAU OF SAFETY AND ENVIRONMENTAL... analysis, under 30 CFR 550.303, to determine the potential effect of facility emissions. The...

  14. 30 CFR 250.1164 - What are the requirements for flaring or venting gas containing H2S?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 2 2012-07-01 2012-07-01 false What are the requirements for flaring or venting gas containing H2S? 250.1164 Section 250.1164 Mineral Resources BUREAU OF SAFETY AND ENVIRONMENTAL... analysis, under 30 CFR 550.303, to determine the potential effect of facility emissions. The...

  15. 30 CFR 250.1164 - What are the requirements for flaring or venting gas containing H2S?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 2 2013-07-01 2013-07-01 false What are the requirements for flaring or venting gas containing H2S? 250.1164 Section 250.1164 Mineral Resources BUREAU OF SAFETY AND ENVIRONMENTAL... analysis, under 30 CFR 550.303, to determine the potential effect of facility emissions. The...

  16. Metal oxide membranes for gas separation

    DOEpatents

    Anderson, M.A.; Webster, E.T.; Xu, Q.

    1994-08-30

    A method for formation of a microporous ceramic membrane onto a porous support includes placing a colloidal suspension of metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane having mean pore sizes less than 30 Angstroms and useful for ultrafiltration, reverse osmosis, or gas separation. 4 figs.

  17. Metal oxide membranes for gas separation

    DOEpatents

    Anderson, Marc A.; Webster, Elizabeth T.; Xu, Qunyin

    1994-01-01

    A method for permformation of a microporous ceramic membrane onto a porous support includes placing a colloidal suspension of metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane having mean pore sizes less than 30 Angstroms and useful for ultrafiltration, reverse osmosis, or gas separation.

  18. Global rate and distribution of H2 gas produced by serpentinization within oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Worman, Stacey L.; Pratson, Lincoln F.; Karson, Jeffrey A.; Klein, Emily M.

    2016-06-01

    It has recently been estimated that serpentinization within continental lithosphere produces H2 at rates comparable to oceanic lithosphere (both are ~1011 mol H2/yr). Here we present a simple model that suggests that H2 production rates along the mid-oceanic ridge alone (i.e., excluding other marine settings) may exceed continental production by an order of magnitude (~1012 mol H2/yr). In our model, H2 production rates increase with spreading rate and the net thickness of serpentinizing peridotite (S-P) in a column of lithosphere. Lithosphere with a faster spreading rate therefore requires a relatively smaller net thickness of S-P to produce H2 at the same rate as lithosphere with a slower rate and greater thickness of S-P. We apply our model globally, incorporating an inverse relationship between spreading rate and net thickness of S-P to be consistent with observations that serpentinization is more common within lithosphere spreading at slower rates.

  19. Metering Gas Strut for Separating Rocket Stages

    NASA Technical Reports Server (NTRS)

    Floyd, Brian

    2010-01-01

    A proposed gas strut system would separate a liquid-fueled second rocket stage from a solid-fueled first stage using an array of pre-charged struts. The strut would be a piston-and-cylinder mechanism containing a compressed gas. Adiabatic expansion of the gas would drive the extension of the strut. The strut is designed to produce a force-versus-time profile, chosen to prevent agitation of the liquid fuel, in which the force would increase from an initial low value to a peak value, then decay toward the end of the stroke. The strut would include a piston chamber and a storage chamber. The piston chamber would initially contain gas at a low pressure to provide the initial low separation force. The storage chamber would contain gas at a higher pressure. The piston would include a longitudinal metering rod containing an array of small holes, sized to restrict the flow gas between the chambers, that would initially not be exposed to the interior of the piston chamber. During subsequent expansion, the piston motion would open more of the metering holes between the storage and piston chambers, thereby increasing the flow of gas into the piston chamber to produce the desired buildup of force.

  20. Gas separation using ultrasound and light absorption

    DOEpatents

    Sinha, Dipen N [Los Alamos, NM

    2012-07-31

    An apparatus and method for separating a chosen gas from a mixture of gases having no moving parts and utilizing no chemical processing is described. The separation of particulates from fluid carriers thereof has been observed using ultrasound. In a similar manner, molecular species may be separated from carrier species. It is also known that light-induced drift may separate light-absorbing species from carrier species. Therefore, the combination of temporally pulsed absorption of light with ultrasonic concentration is expected to significantly increase the efficiency of separation by ultrasonic concentration alone. Additionally, breaking the spatial symmetry of a cylindrical acoustic concentrator decreases the spatial distribution of the concentrated particles, and increases the concentration efficiency.

  1. Pump Propels Liquid And Gas Separately

    NASA Technical Reports Server (NTRS)

    Harvey, Andrew; Demler, Roger

    1993-01-01

    Design for pump that handles mixtures of liquid and gas efficiently. Containing only one rotor, pump is combination of centrifuge, pitot pump, and blower. Applications include turbomachinery in powerplants and superchargers in automobile engines. Efficiencies lower than those achieved in separate components. Nevertheless, design is practical and results in low consumption of power.

  2. Formation of hydrogenated amorphous carbon films by reactive high power impulse magnetron sputtering containing C2H2 gas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    Diamond-like carbon (DLC) films have attracted interest for material industries, because they have unique properties. Hydrogenated amorphous carbon films are prepared by reactive high power impulse magnetron sputtering (HiPIMS) containing C2H2 gas and the properties of the films produced in Ar/C2H2 and Ne/C2H2 HiPIMS are compared. Production of hydrocarbon radicals and their ions strongly depends on both electron temperature and electron density in HiPIMS. Therefore, the influence of the difference in buffer gas (Ar and Ne) on the film properties is also valuable to investigate. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 35 A. A negative pulse voltage is applied to the substrates for about 15 μs after the target voltage changed from about -500 V to 0 V. Hardness of the films prepared by Ar/C2H2 HiPIMS monotonically decreases with increasing the total pressure, whereas that of the films prepared by Ne/C2H2 HiPIMS does not strongly depend on the total pressure. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  3. Photocatalytic oxidation of H2S in the gas phase over TiO2-coated glass fiber filter.

    PubMed

    Brancher, Marlon; Franco, Davide; de Melo Lisboa, Henrique

    2016-11-01

    To promote the photocatalytic oxidation (PCO) of hydrogen sulfide (H2S) in the gas phase, TiO2-coated glass fiber filters were packed in an annular photoreactor. Glass fibers coated with TiO2 thin films were characterized structurally and morphologically by field emission gun scanning electron microscopy (FEG-SEM), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Flow rate and H2S inlet concentration were evaluated to determine the performance of the reactor. Removal efficiencies up to 99% were achieved for flow rate of 25 L h(-1) (residence time of 121 s) and H2S inlet concentration from 12 to 14 ppmv. The long-term experiment presented H2S removal of 89% for 16 h. After 28 h of continuous use, H2S degradation was observed at 64%, which suggests that the photocatalyst was losing activity due to deactivation. Moreover, the kinetics of the PCO of H2S according to the Langmuir-Hinshelwood (L-H) approach along with the mass balance of a plug-flow reactor was modeled. The reaction constant (k) was calculated at approximately 10.5 μmol m(-3) s(-1) and the adsorption constant (K) of approximately 5263 m(-3) mol with linearity (R2) of 0.98.

  4. H2S gas biological removal efficiency and bacterial community diversity in biofilter treating wastewater odor.

    PubMed

    Omri, Ilhem; Bouallagui, Hassib; Aouidi, Fathia; Godon, Jean-Jacques; Hamdi, Moktar

    2011-11-01

    The objective of this study was to assess the feasibility of using a biofilter system to treat hydrogen sulfide (H2S) contaminated air and to characterize its microbial community. The biofilter system was packed with peat. During the experimental work, the peat was divided in three layers (down, middle, and up). Satisfactory removal efficiencies of H2S were proved and reached 99% for the majority of the run time at an empty bed retention time (EBRT) of 60 s. The polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method was used to uncover the changes in the microbial community between the different layers. Analysis of SSCP profiles demonstrated significant differences in community structure from a layer to another with a strong decrease in species diversity towards the up layer. It was found that the used support was suitable for microorganism growth, and may have a potential application in H2S biofiltration system.

  5. Experimental Investigations of the Effects of Acid Gas (H2S/CO2) Exposure under Geological Sequestration Conditions

    NASA Astrophysics Data System (ADS)

    Hawthorne, S. B.; Miller, D.; Kutchko, B. G.; Strazisar, B. R.

    2009-12-01

    Acid gas (mixed CO2 and H2S) injection into geological formations is increasingly used as a disposal option. In contrast to pure CO2 injection, there is little understanding of the possible effects of acid gases under geological sequestration conditions on exposed materials ranging from reactions with reservoir minerals to the stability of proppants injected to improve oil recovery to the possible failure of well-bore cements. The number of laboratory studies investigating effects of acid gas has been limited by safety concerns and the difficulty in preparing and maintaining single-phase H2S/CO2 mixtures under the experimental pressures and temperatures required. We have developed approaches using conventional syringe pumps and reactor vessels to prepare and maintain H2S/CO2 mixtures under relevant sequestration conditions of temperature, pressure, and exposure to water and dissolved salts. These methods have been used to investigate and compare the effects of acid gas with those of pure CO2 on several materials including reservoir cores, oil recovery proppants, and well-bore cements, as well as to investigate the rates of model reactions such as the conversion of Fe3O4 to pyrite. The apparatus and methods used to perform acid gas exposures and representative results from the various exposed materials will be presented.

  6. Adsorption Model for Off-Gas Separation

    SciTech Connect

    Veronica J. Rutledge

    2011-03-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed in gPROMS software. Inputs include gas stream constituents, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. It models dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions for a multiple component gas stream. The simulation outputs component concentrations along the column length as a function of time from which the breakthrough data is obtained. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data will be input into the adsorption model to develop a model specific for iodine adsorption on silver mordenite as well as model(s) specific for krypton and xenon adsorption. The model will be validated with experimental breakthrough curves. Another future off-gas modeling goal is to develop a model for the unit operation absorption. The off-gas models will be made available via the server or web for evaluation by customers.

  7. Selectivity trend of gas separation through nanoporous graphene

    DOE PAGES

    Liu, Hongjun; Chen, Zhongfang; Dai, Sheng; ...

    2014-01-29

    We demonstrate that porous graphene can efficiently separate gases according to their molecular sizes using molecular dynamic (MD) simulations,. The flux sequence from the classical MD simulation is H2>CO2>>N2>Ar>CH4, which generally follows the trend in the kinetic diameters. Moreover, this trend is also confirmed from the fluxes based on the computed free energy barriers for gas permeation using the umbrella sampling method and kinetic theory of gases. Both brute-force MD simulations and free-energy calcualtions lead to the flux trend consistent with experiments. Case studies of two compositions of CO2/N2 mixtures further demonstrate the separation capability of nanoporous graphene.

  8. Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

    NASA Astrophysics Data System (ADS)

    Chu, X. X.; Zhang, M. M.; Zhang, D. X.; Xu, D.; Qian, Y.; Liu, W.

    2014-01-01

    In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H2 from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H2 in helium recycle gas are less than 1 ppb.

  9. Membrane gas absorbers for H2S removal--design, operation and technology integration into existing odour treatment strategies.

    PubMed

    Jefferson, B; Nazareno, C; Georgaki, S; Gostelow, P; Stuetz, R M; Longhurst, P; Robinson, T

    2005-07-01

    A hollow fibre (HF) polypropylene membrane gas absorber was investigated for the removal of hydrogen sulphide (H2S) from gas streams. Gas concentrations between 25-2010 ppmV were fed into the shell side of a membrane module whilst water-NaOH solutions flowed counter-currently in the fibre lumens. The process was effective at removing the H2S (96% at G:L ratios up to 50 and pH 13) from the gas phase in a single pass through the membrane at all the concentrations of HaS investigated. Analysis of the mass transfer process revealed the rate of transfer to be controlled by the gas phase transfer coefficient with a value between 1 and 25 x 10(-4) m.s(-1). The possible integration of a membrane absorber system into existing odour treatment strategies was assessed by comparing the membrane system, based on the experimentally determined mass transfer coefficient, with existing full scale biofiltration plants. The membrane system became economically favourable at gas flow rates lower than 1630 m(3) x h(-1).

  10. A thermodynamical model for the surface tension of silicate melts in contact with H2O gas

    NASA Astrophysics Data System (ADS)

    Colucci, Simone; Battaglia, Maurizio; Trigila, Raffaello

    2016-02-01

    Surface tension plays an important role in the nucleation of H2O gas bubbles in magmatic melts and in the time-dependent rheology of bubble-bearing magmas. Despite several experimental studies, a physics based model of the surface tension of magmatic melts in contact with H2O is lacking. This paper employs gradient theory to develop a thermodynamical model of equilibrium surface tension of silicate melts in contact with H2O gas at low to moderate pressures. In the last decades, this approach has been successfully applied in studies of industrial mixtures but never to magmatic systems. We calibrate and verify the model against literature experimental data, obtained by the pendant drop method, and by inverting bubble nucleation experiments using the Classical Nucleation Theory (CNT). Our model reproduces the systematic decrease in surface tension with increased H2O pressure observed in the experiments. On the other hand, the effect of temperature is confirmed by the experiments only at high pressure. At atmospheric pressure, the model shows a decrease of surface tension with temperature. This is in contrast with a number of experimental observations and could be related to microstructural effects that cannot be reproduced by our model. Finally, our analysis indicates that the surface tension measured inverting the CNT may be lower than the value measured by the pendant drop method, most likely because of changes in surface tension controlled by the supersaturation.

  11. A thermodynamical model for the surface tension of silicate melts in contact with H2O gas

    USGS Publications Warehouse

    Colucci, Simone; Battaglia, Maurizio; Trigila, Raffaello

    2016-01-01

    Surface tension plays an important role in the nucleation of H2O gas bubbles in magmatic melts and in the time-dependent rheology of bubble-bearing magmas. Despite several experimental studies, a physics based model of the surface tension of magmatic melts in contact with H2O is lacking. This paper employs gradient theory to develop a thermodynamical model of equilibrium surface tension of silicate melts in contact with H2O gas at low to moderate pressures. In the last decades, this approach has been successfully applied in studies of industrial mixtures but never to magmatic systems. We calibrate and verify the model against literature experimental data, obtained by the pendant drop method, and by inverting bubble nucleation experiments using the Classical Nucleation Theory (CNT). Our model reproduces the systematic decrease in surface tension with increased H2O pressure observed in the experiments. On the other hand, the effect of temperature is confirmed by the experiments only at high pressure. At atmospheric pressure, the model shows a decrease of surface tension with temperature. This is in contrast with a number of experimental observations and could be related to microstructural effects that cannot be reproduced by our model. Finally, our analysis indicates that the surface tension measured inverting the CNT may be lower than the value measured by the pendant drop method, most likely because of changes in surface tension controlled by the supersaturation.

  12. Optimization of operating parameters for gas-phase photocatalytic splitting of H2S by novel vermiculate packed tubular reactor.

    PubMed

    Preethi, V; Kanmani, S

    2016-10-01

    Hydrogen production by gas-phase photocatalytic splitting of Hydrogen Sulphide (H2S) was investigated on four semiconductor photocatalysts including CuGa1.6Fe0.4O2, ZnFe2O3, (CdS + ZnS)/Fe2O3 and Ce/TiO2. The CdS and ZnS coated core shell particles (CdS + ZnS)/Fe2O3 shows the highest rate of hydrogen (H2) production under optimized conditions. Packed bed tubular reactor was used to study the performance of prepared photocatalysts. Selection of the best packing material is a key for maximum removal efficiency. Cheap, lightweight and easily adsorbing vermiculate materials were used as a novel packing material and were found to be effective in splitting H2S. Effect of various operating parameters like flow rate, sulphide concentration, catalyst dosage, light irradiation were tested and optimized for maximum H2 conversion of 92% from industrial waste H2S.

  13. Molecular gas in low-metallicity starburst galaxies:. Scaling relations and the CO-to-H2 conversion factor

    NASA Astrophysics Data System (ADS)

    Amorín, R.; Muñoz-Tuñón, C.; Aguerri, J. A. L.; Planesas, P.

    2016-04-01

    Context. Tracing the molecular gas-phase in low-mass star-forming galaxies becomes extremely challenging due to significant UV photo-dissociation of CO molecules in their low-dust, low-metallicity ISM environments. Aims: We aim to study the molecular content and the star-formation efficiency of a representative sample of 21 blue compact dwarf galaxies (BCDs), previously characterized on the basis of their spectrophotometric properties. Methods: We present CO (1-0) and (2-1) observations conducted at the IRAM-30m telescope. These data are further supplemented with additional CO measurements and multiwavelength ancillary data from the literature. We explore correlations between the derived CO luminosities and several galaxy-averaged properties. Results: We detect CO emission in seven out of ten BCDs observed. For two galaxies these are the first CO detections reported so far. We find the molecular content traced by CO to be correlated with the stellar and Hi masses, star formation rate (SFR) tracers, the projected size of the starburst, and its gas-phase metallicity. BCDs appear to be systematically offset from the Schmidt-Kennicutt (SK) law, showing lower average gas surface densities for a given ΣSFR, and therefore showing extremely low (≲0.1 Gyr) H2 and H2 +Hi depletion timescales. The departure from the SK law is smaller when considering H2 +Hi rather than H2 only, and is larger for BCDs with lower metallicity and higher specific SFR. Thus, the molecular fraction (ΣH2/ ΣHI) and CO depletion timescale (ΣH2/ ΣSFR) of BCDs is found to be strongly correlated with metallicity. Using this, and assuming that the empirical correlation found between the specific SFR and galaxy-averaged H2 depletion timescale of more metal-rich galaxies extends to lower masses, we derive a metallicity-dependent CO-to-H2 conversion factor αCO,Z ∝ (Z/Z⊙)- y, with y = 1.5(±0.3)in qualitative agreement with previous determinations, dust-based measurements, and recent model

  14. First accurate experimental study of Mu reactivity from a state-selected reactant in the gas phase: the Mu + H2{1} reaction rate at 300 K

    NASA Astrophysics Data System (ADS)

    Bakule, Pavel; Sukhorukov, Oleksandr; Ishida, Katsuhiko; Pratt, Francis; Fleming, Donald; Momose, Takamasa; Matsuda, Yasuyuki; Torikai, Eiko

    2015-02-01

    This paper reports on the experimental background and methodology leading to recent results on the first accurate measurement of the reaction rate of the muonium (Mu) atom from a state-selected reactant in the gas phase: the Mu + H2\\{1\\}\\to MuH + H reaction at 300 K, and its comparison with rigorous quantum rate theory, Bakule et al (2012 J. Phys. Chem. Lett. 3 2755). Stimulated Raman pumping, induced by 532 nm light from the 2nd harmonic of a Nd:YAG laser, was used to produce H2 in its first vibrational (v = 1) state, H2\\{1\\}, in a single Raman/reaction cell. A pulsed muon beam (from ‘ISIS’, at 50 Hz) matched the 25 Hz repetition rate of the laser, allowing data taking in equal ‘Laser-On/Laser-Off’ modes of operation. The signal to noise was improved by over an order of magnitude in comparison with an earlier proof-of-principle experiment. The success of the present experiment also relied on optimizing the overlap of the laser profile with the extended stopping distribution of the muon beam at 50 bar H2 pressure, in which Monte Carlo simulations played a central role. The rate constant, found from the analysis of three separate measurements, which includes a correction for the loss of {{H}2}\\{1\\} concentration due to collisional relaxation with unpumped H2 during the time of each measurement, is {{k}Mu}\\{1\\} = 9.9[(-1.4)(+1.7)] × 10-13 cm3 s-1 at 300 K. This is in good to excellent agreement with rigorous quantum rate calculations on the complete configuration interaction/Born-Huang surface, as reported earlier by Bakule et al, and which are also briefly commented on herein.

  15. [Performance of cross flow trickling filter for H2S gas treatment].

    PubMed

    Liu, Chun-Jing; Li, Jian; Liu, Jia; Peng, Shu-Jing; Li, Chao; Chen, Ying; He, Hong

    2012-09-01

    A grading cross bio-trickling filter was designed for H2S removal. Mixed microorganisms domesticated from the former experiment were immobilized to start up the trickling filter. Removal performances during starting up period and different loadings were investigated. Results showed that the immobilization of the trickling filter was completed within 3 d. The removal efficiency was higher than 99% when the inlet concentration was in the range of 110 mg x m(-3) to 230 mg x m(-3) (EBRT 30 s). At low inlet loadings, the front part of the trickling filter played a major role in H2S degradation, accounting for about 85%. Microbial diversity and population of the front part were superior to the tail one. At higher loadings, microbial diversity and population of the tail part increased significantly, from 4.5 x 10(7) cells x g (-1) to 5.17 x 10(8) cells x g(-1), and the elimination capacity was also improved,from 0.04 g x h(-1) to 0.67 g x h(-1). Rod-shaped bacteria were the dominant microorganisms on the surface of ceramics in the steady state as observed by SEM. The surfaces of ceramics were covered by a lot of microbial metabolites at high loadings. Analysis of the metabolites indicated that the majority of H2S was oxidized to sulfur and only a small portion was converted to sulfate.

  16. The RealGas and RealGasH2O options of the TOUGH+ code for the simulation of coupled fluid and heat flow in tight/shale gas systems

    EPA Science Inventory

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas. The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and sh...

  17. Optimization of an enclosed gas analyzer sampling system for measuring eddy covariance fluxes of H2O and CO2

    NASA Astrophysics Data System (ADS)

    Metzger, Stefan; Burba, George; Burns, Sean P.; Blanken, Peter D.; Li, Jiahong; Luo, Hongyan; Zulueta, Rommel C.

    2016-03-01

    Several initiatives are currently emerging to observe the exchange of energy and matter between the earth's surface and atmosphere standardized over larger space and time domains. For example, the National Ecological Observatory Network (NEON) and the Integrated Carbon Observing System (ICOS) are set to provide the ability of unbiased ecological inference across ecoclimatic zones and decades by deploying highly scalable and robust instruments and data processing. In the construction of these observatories, enclosed infrared gas analyzers are widely employed for eddy covariance applications. While these sensors represent a substantial improvement compared to their open- and closed-path predecessors, remaining high-frequency attenuation varies with site properties and gas sampling systems, and requires correction. Here, we show that components of the gas sampling system can substantially contribute to such high-frequency attenuation, but their effects can be significantly reduced by careful system design. From laboratory tests we determine the frequency at which signal attenuation reaches 50 % for individual parts of the gas sampling system. For different models of rain caps and particulate filters, this frequency falls into ranges of 2.5-16.5 Hz for CO2, 2.4-14.3 Hz for H2O, and 8.3-21.8 Hz for CO2, 1.4-19.9 Hz for H2O, respectively. A short and thin stainless steel intake tube was found to not limit frequency response, with 50 % attenuation occurring at frequencies well above 10 Hz for both H2O and CO2. From field tests we found that heating the intake tube and particulate filter continuously with 4 W was effective, and reduced the occurrence of problematic relative humidity levels (RH > 60 %) by 50 % in the infrared gas analyzer cell. No further improvement of H2O frequency response was found for heating in excess of 4 W. These laboratory and field tests were reconciled using resistor-capacitor theory, and NEON's final gas sampling system was developed on this

  18. An approach for estimating toxic releases of H2S-containing natural gas.

    PubMed

    Jianwen, Zhang; Da, Lei; Wenxing, Feng

    2014-01-15

    China is well known being rich in sulfurous natural gas with huge deposits widely distributed all over the country. Due to the toxic nature, the release of hydrogen sulfide-containing natural gas from the pipelines intends to impose serious threats to the human, society and environment around the release sources. CFD algorithm is adopted to simulate the dispersion process of gas, and the results prove that Gaussian plume model is suitable for determining the affected region of the well blowout of sulfide hydrogen-containing natural gas. In accordance with the analysis of release scenarios, the present study proposes a new approach for estimating the risk of hydrogen sulfide poisoning hazards, as caused by sulfide-hydrogen-containing natural gas releases. Historical accident-statistical data from the EGIG (European Gas Pipeline Incident Data Group) and the Britain Gas Transco are integrated into the approach. Also, the dose-load effect is introduced to exploit the hazards' effects by two essential parameters - toxic concentration and exposure time. The approach was applied to three release scenarios occurring on the East-Sichuan Gas Transportation Project, and the individual risk and societal risk are classified and discussed. Results show that societal risk varies significantly with different factors, including population density, distance from pipeline, operating conditions and so on. Concerning the dispersion process of hazardous gas, available safe egress time was studied from the perspective of individual fatality risks. The present approach can provide reliable support for the safety management and maintenance of natural gas pipelines as well as evacuations that may occur after release incidents.

  19. Four-port gas separation membrane module assembly

    DOEpatents

    Wynn, Nicholas P.; Fulton, Donald A.; Lokhandwala, Kaaeid A.; Kaschemekat, Jurgen

    2010-07-20

    A gas-separation membrane assembly, and a gas-separation process using the assembly. The assembly incorporates multiple gas-separation membranes in an array within a single vessel or housing, and is equipped with two permeate ports, enabling permeate gas to be withdrawn from both ends of the membrane module permeate pipes.

  20. Optimization of a gas sampling system for measuring eddy-covariance fluxes of H2O and CO2

    NASA Astrophysics Data System (ADS)

    Metzger, S.; Burba, G.; Burns, S. P.; Blanken, P. D.; Li, J.; Luo, H.; Zulueta, R. C.

    2015-10-01

    Several initiatives are currently emerging to observe the exchange of energy and matter between the earth's surface and atmosphere standardized over larger space and time domains. For example, the National Ecological Observatory Network (NEON) and the Integrated Carbon Observing System (ICOS) will provide the ability of unbiased ecological inference across eco-climatic zones and decades by deploying highly scalable and robust instruments and data processing. In the construction of these observatories, enclosed infrared gas analysers are widely employed for eddy-covariance applications. While these sensors represent a substantial improvement compared to their open- and closed-path predecessors, remaining high-frequency attenuation varies with site properties, and requires correction. Here, we show that the gas sampling system substantially contributes to high-frequency attenuation, which can be minimized by careful design. From laboratory tests we determine the frequency at which signal attenuation reaches 50 % for individual parts of the gas sampling system. For different models of rain caps and particulate filters, this frequency falls into ranges of 2.5-16.5 Hz for CO2, 2.4-14.3 Hz for H2O, and 8.3-21.8 Hz for CO2, 1.4-19.9 Hz for H2O, respectively. A short and thin stainless steel intake tube was found to not limit frequency response, with 50 % attenuation occurring at frequencies well above 10 Hz for both H2O and CO2. From field tests we found that heating the intake tube and particulate filter continuously with 4 W was effective, and reduced the occurrence of problematic relative humidity levels (RH > 60 %) by 50 % in the infrared gas analyser cell. No further improvement of H2O frequency response was found for heating in excess of 4 W. These laboratory and field tests were reconciled using resistor-capacitor theory, and NEON's final gas sampling system was developed on this basis. The design consists of the stainless steel intake tube, a pleated mesh

  1. Gas storage and separation by electric field swing adsorption

    DOEpatents

    Currier, Robert P; Obrey, Stephen J; Devlin, David J; Sansinena, Jose Maria

    2013-05-28

    Gases are stored, separated, and/or concentrated. An electric field is applied across a porous dielectric adsorbent material. A gas component from a gas mixture may be selectively separated inside the energized dielectric. Gas is stored in the energized dielectric for as long as the dielectric is energized. The energized dielectric selectively separates, or concentrates, a gas component of the gas mixture. When the potential is removed, gas from inside the dielectric is released.

  2. KINETICS OF DIRECT OXIDATION OF H2S IN COAL GAS TO ELEMENTAL SULFUR

    SciTech Connect

    K.C. Kwon

    2002-02-01

    Removal of hydrogen sulfide (H{sub 2}S) from coal gasifier gas and sulfur recovery are key steps in the development of Department of Energy's (DOE's) advanced Vision 21 plants that employ coal and natural gas and produce electric power and clean transportation fuels. These Vision 21 plants will require highly clean coal gas with H{sub 2}S below 1 ppm and negligible amounts of trace contaminants such as hydrogen chloride, ammonia, alkali, heavy metals, and particulate. The conventional method of sulfur removal and recovery employing amine, Claus, and tail-gas treatment is very expensive. A second generation approach developed under DOE's sponsorship employs hot-gas desulfurization (HGD) using regenerable metal oxide sorbents followed by Direct Sulfur Recovery Process (DSRP). However, this process sequence does not remove trace contaminants and is targeted primarily towards the development of advanced integrated gasification combined cycle (IGCC) plants that produce electricity (not both electricity and transportation fuels). There is an immediate as well as long-term need for the development of cleanup processes that produce highly clean coal gas for next generation Vision 21 plants. To this end, a novel process is now under development at Research Triangle Institute (RTI) in which the H{sub 2}S in coal gas is directly oxidized to elemental sulfur over a selective catalyst. Such a process is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H{sub 2}S. This direct oxidation process has the potential to produce a super clean coal gas more economically than both conventional amine-based processes and HGD/DSRP. The objective of this research is to support the near- and long-term DOE efforts to commercialize this direct oxidation technology. Specifically, we aim to: Measure the kinetics of direct oxidation of H{sub 2}S to elemental sulfur over selective catalysts in the presence of major

  3. Modeling gas-phase H2O between 5 μ m and 540 μ m toward massive protostars

    NASA Astrophysics Data System (ADS)

    Boonman, A. M. S.; Doty, S. D.; van Dishoeck, E. F.; Bergin, E. A.; Melnick, G. J.; Wright, C. M.; Stark, R.

    2003-08-01

    We present models and observations of gas-phase H2O lines between 5 and 540 mu m toward deeply embedded massive protostars, involving both pure rotational and ro-vibrational transitions. The data have been obtained for 6 sources with both the Short and Long Wavelength Spectrometers (SWS and LWS) on board the Infrared Space Observatory (ISO) and with the Submillimeter Wave Astronomy Satellite (SWAS). For comparison, CO J=7-6 spectra have been observed with the MPIfR/SRON 800 GHz heterodyne spectrometer at the James Clerk Maxwell Telescope (JCMT). A radiative transfer model in combination with different physical/chemical scenarios has been used to model these H2O lines for 4 sources to probe the chemical structure of these massive protostars. The results indicate that pure gas-phase production of H2O cannot explain the observed spectra. Ice evaporation in the warm inner envelope and freeze-out in the cold outer part are important for most of our sources and occur at T ~ 90-110 K. The ISO-SWS data are particularly sensitive to ice evaporation in the inner part whereas the ISO-LWS data are good diagnostics of freeze-out in the outer region. The modeling suggests that the 557 GHz SWAS line includes contributions from both the cold and the warm H2O gas. The SWAS line profiles indicate that for some of the sources a fraction of up to 50% of the total flux may originate in the outflow. Shocks do not seem to contribute significantly to the observed emission in other H2O lines, however, in contrast with the case for Orion. The results show that three of the observed and modeled H2O lines, the 303-212, 212-101, and 110-101 lines, are good candidates to observe with the Herschel Space Observatory in order to further investigate the physical and chemical conditions in massive star-forming regions. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and UK) and with the

  4. Disposable, Paper-Based, Inkjet-Printed Humidity and H2S Gas Sensor for Passive Sensing Applications

    PubMed Central

    Quddious, Abdul; Yang, Shuai; Khan, Munawar M.; Tahir, Farooq A.; Shamim, Atif; Salama, Khaled N.; Cheema, Hammad M.

    2016-01-01

    An inkjet-printed, fully passive sensor capable of either humidity or gas sensing is presented herein. The sensor is composed of an interdigitated electrode, a customized printable gas sensitive ink and a specialized dipole antenna for wireless sensing. The interdigitated electrode printed on a paper substrate provides the base conductivity that varies during the sensing process. Aided by the porous nature of the substrate, a change in relative humidity from 18% to 88% decreases the electrode resistance from a few Mega-ohms to the kilo-ohm range. For gas sensing, an additional copper acetate-based customized ink is printed on top of the electrode, which, upon reaction with hydrogen sulphide gas (H2S) changes, both the optical and the electrical properties of the electrode. A fast response time of 3 min is achieved at room temperature for a H2S concentration of 10 ppm at a relative humidity (RH) of 45%. The passive wireless sensing is enabled through an antenna in which the inner loop takes care of conductivity changes in the 4–5 GHz band, whereas the outer-dipole arm is used for chipless identification in the 2–3 GHz band. PMID:27929450

  5. H2O and HCl trace gas kinetics on crystalline and amorphous HCl hydrates in the range 170 to 205 K: the HCl/H2O phase diagram revisited

    NASA Astrophysics Data System (ADS)

    Iannarelli, R.; Rossi, M. J.

    2013-11-01

    In this laboratory study, H2O ice films of 1 to 2 μm thickness have been used as surrogates for ice particles at atmospherically relevant conditions in a stirred flow reactor (SFR) to measure the kinetics of evaporation and condensation of HCl and H2O on crystalline and amorphous HCl hydrates. A multidiagnostic approach has been employed using FTIR absorption spectroscopy in transmission to monitor the condensed phase and residual gas mass spectrometry (MS) for the gas phase. An average mass balance ratio between HCl adsorbed onto ice and the quantity of HCl measured using FTIR absorption, (Nn - Nesc - Nads)/NFTIR = 1.182 ± 0.123 has been obtained. The rate of evaporation Rev(HCl) for crystalline HCl hexahydrate (HCl·6H2O) films and amorphous HCl/H2O mixtures has been found to be lower by a factor of 10 to 250 compared to Rev(H2O) in the overlapping temperature range 175 to 190 K. Variations of the accommodation coefficient α (HCl) on pure HCl·6H2O up to a factor of 10 have been observed. The kinetic parameters are thermochemically consistent with the corresponding equilibrium vapour pressure. In addition, we propose an extension of the HCl/H2O phase diagram of crystalline HCl·6H2O based on the analysis of deconvoluted FTIR spectra of samples outside its known existence area. A brief evaluation of the atmospheric importance of both condensed phases, amorphous HCl/H2O and crystalline HCl·6H2O, is performed in favour of the amorphous phase.

  6. Growth conditions effects on the H2 and CO2 gas sensing properties of Indium Tin Oxide

    NASA Astrophysics Data System (ADS)

    Isik, S.; Coban, O.; Shafai, C.; Tuzemen, S.; Gur, E.

    2016-04-01

    Indium Tin Oxide (ITO) thin films are transparent conducting wide bandgap oxide. In this study investigated optical, structural and morphological properties of sputtered ITO thin films using X-ray diffraction spectroscopy (XRD), Scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and optical absorption techniques. These measurements revealed that the oxygen gas percentage present in the ITO film deposited by RF magnetron sputter deposition showed systematic variation of its band gap, crystal orientation, growth rate, figure of merit (FOM) and dominant XRD peaks. All the thin films deposited at room temperature (RT). Once characterization of the films carried out, H2 and CO2 resistive gas sensors fabricated by depositing the ITO film on top of aluminium interdigitated contacts/electrode (IDE), that fabricated following lithography and etching processes. These devices showed reasonable sensitivity for pure H2 and CO2 at elevated temperature. A correlation found between the thin film properties of the ITO and its sensing capability for H2 and CO2, which these gases are important in many fields such as automotive, energy, biological and health-related applications.

  7. Kinetics of Direct Oxidation of H2S in Coal Gas to Elemental Sulfur

    SciTech Connect

    K.C. Kwon

    2005-11-01

    Removal of hydrogen sulfide (H{sub 2}S) from coal gasifier gas and sulfur recovery are key steps in the development of Department of Energy's (DOE's) advanced Vision 21 plants that produce electric power and clean transportation fuels with coal and natural gas. These Vision 21 plants will require highly clean coal gas with H{sub 2}S below 1 ppm and negligible amounts of trace contaminants such as hydrogen chloride, ammonia, alkali, heavy metals, and particulate. The conventional method of sulfur removal and recovery employing amine, Claus, and tail-gas treatment is very expensive. A second generation approach developed under DOE's sponsorship employs hot-gas desulfurization (HGD) using regenerable metal oxide sorbents followed by Direct Sulfur Recovery Process (DSRP). However, this process sequence does not remove trace contaminants and is targeted primarily towards the development of advanced integrated gasification combined cycle (IGCC) plants that produce electricity (not both electricity and transportation fuels). There is an immediate as well as long-term need for the development of cleanup processes that produce highly clean coal gas for next generation Vision 21 plants. To this end, a novel process is now under development at several research organizations in which the H{sub 2}S in coal gas is directly oxidized to elemental sulfur over a selective catalyst. Such a process is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H{sub 2}S. The direct oxidation of H{sub 2}S to elemental sulfur in the presence of SO{sub 2} is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H{sub 2}S. This direct oxidation process has the potential to produce a super clean coal gas more economically than both conventional amine-based processes and HGD/DSRP. The objectives of this research are to measure kinetics of direct

  8. Merging open metal sites and Lewis basic sites in a NbO-type metal-organic framework for improved C2H2/CH4 and CO2/CH4 separation.

    PubMed

    Song, Chengling; Hu, Jiayi; Ling, Yajing; Feng, Yunlong; Chen, De-Li; He, Yabing

    2015-09-07

    A new three-dimensional NbO-type porous metal-organic framework ZJNU-47 was synthesized via a solvothermal reaction of Cu(NO3)2·3H2O and a Lewis basic nitrogen donor site-rich tetracarboxylate, namely, 5,5'-(pyridazine-3,6-diyl)-diisophthalate, and the structure was characterized by single-crystal X-ray diffraction to be isostructural with NOTT-101. With the synergistic effect of open metal sites, Lewis basic sites and a suitable pore space, the MOF material ZJNU-47a after activation can take up a large amount of C2H2 and CO2. The gravimetric C2H2 uptake of 214 cm(3) (STP) g(-1) at room temperature and 1 atm is the highest among all reported MOFs to date, and the gravimetric CO2 uptake of 108 cm(3) (STP) g(-1) is also among the highest reported for MOFs. Compared to the isostructural MOF NOTT-101a, ZJNU-47a exhibits a significant increase in C2H2 and CO2 uptake and thus improved C2H2/CH4 and CO2/CH4 separations. Significantly, comprehensive DFT studies of C2H2 and CO2 adsorption have revealed that the open nitrogen donor sites are comparable and even superior to open metal sites regarding the adsorption sites. This work demonstrated that the simultaneous introduction of Lewis basic nitrogen donor sites and Lewis acidic metal sites into the framework is a promising approach to improve the gas sorption toward CO2 and C2H2 and thus to produce materials possessing enhanced C2H2/CH4 and CO2/CH4 separation performance.

  9. Permeable polyaniline articles for gas separation

    DOEpatents

    Wang, Hsing-Lin; Mattes, Benjamin R.

    2004-09-28

    Immersion precipitation of solutions having 15%-30% (w/w) and various molecular weights of the emeraldine base form of polyaniline in polar aprotic solvents are shown to form integrally skinned asymmetric membranes and fibers having skin layers <1 .mu.m thick which exhibit improved rates of gas transport while preserving good selectivity. These membranes can be further transformed by an acid doping process after fabrication to achieve excellent permeation rates and high selectivities for particular gas separations. Prior to the use of concentrated EB solutions, the formation of integrally skinned asymmetric membranes was not possible, since films and fibers made from <5% w/w polyaniline solutions were found to disintegrate during the IP process.

  10. Permeable polyaniline articles for gas separation

    DOEpatents

    Wang, Hsing-Lin; Mattes, Benjamin R.

    2009-07-21

    Immersion precipitation of solutions having 15%-30% (w/w) and various molecular weights of the emeraldine base form of polyaniline in polar aprotic solvents are shown to form integrally skinned asymmetric membranes and fibers having skin layers <1 .mu.m thick which exhibit improved rates of gas transport while preserving good selectivity. These membranes can be further transformed by an acid doping process after fabrication to achieve excellent permeation rates and high selectivities for particular gas separations. Prior to the use of concentrated EB solutions, the formation of integrally skinned asymmetric membranes was not possible, since films and fibers made from <5% w/w polyaniline solutions were found to disintegrate during the IP process.

  11. Rate constants of atomic hydrogen formation in H3O+(H2O) n + e → H + (H2O) n gas-phase processes

    NASA Astrophysics Data System (ADS)

    Stepanov, N. F.; Novakovskaya, Yu. V.

    2009-09-01

    Using the Maxwellian electron velocity distribution and the Breit-Wigner approximation of the reaction cross section, the kinetic parameters of the hydrogen atom formation upon the electron capture by positively charged hydronium-water clusters are estimated. Calculations of the cross sections and rate constants are based on the data of quantum chemical studies of H3O+(H2O) n and H3O(H2O) n clusters, particularly on the detailed analysis of the spacing of high-lying states of the radicals and the character of the unpaired electron density distribution, as well as on the general trend in the electron affinity change of the cations depending on the number of water molecules. The lifetimes of the radicals before the dissociation are taken from the classical nonempirical molecular dynamics runs. The results are compared to available experimental data.

  12. ASU nitrogen sweep gas in hydrogen separation membrane for production of HRSG duct burner fuel

    SciTech Connect

    Panuccio, Gregory J.; Raybold, Troy M.; Jamal, Agil; Drnevich, Raymond Francis

    2013-04-02

    The present invention relates to the use of low pressure N2 from an air separation unit (ASU) for use as a sweep gas in a hydrogen transport membrane (HTM) to increase syngas H2 recovery and make a near-atmospheric pressure (less than or equal to about 25 psia) fuel for supplemental firing in the heat recovery steam generator (HRSG) duct burner.

  13. Synthesis of activated carbon from oil fly ash for removal of H2S from gas stream

    NASA Astrophysics Data System (ADS)

    Aslam, Zaheer; Shawabkeh, Reyad A.; Hussein, Ibnelwaleed A.; Al-Baghli, Nadhir; Eic, Mladen

    2015-02-01

    Activated carbon (AC) is made from waste oil fly ash (OFA) which is produced in large quantities from power generation plants through combustion of heavy fuel oil. OFA contains ∼80% carbon that makes it suitable for producing AC by physicochemical treatments using a mixture of HNO3, H2SO4, and H3PO4 acids to remove non-carbonaceous impurities. The acid treated OFA is then activated by CO2 at 990 °C. The physico-chemical treatments of OFA have increased the surface area from 4 to 375 m2/g. Surface morphology and pore volume of AC are characterized by combined SEM and EDX techniques. Elemental analysis shows that sulfur content is reduced from 7.1 wt% in untreated OFA to 0.51 wt% for the treated OFA. The AC is further treated with HNO3 and NH4OH solutions in order to attach the carboxylic and amine groups on the surface, respectively. FTIR characterization is used to confirm the presence of the functional groups on the surface of AC at different stages of its development. The performance of functionalized AC samples is tested for the removal of H2S from a synthetic natural gas by carrying out breakthrough experiments. The results from these tests have shown maximum adsorption capacity of 0.3001 mg/g for NH4OH functionalized activated carbon with 86.43% regeneration efficiency. The ammonium hydroxide treated AC is found to be more effective for H2S removal than acid treated AC as confirmed by breakthrough experiments. The results indicate that the presence of more acidic functionalities on the surface reduces the H2S adsorption efficiency from the gas mixture.

  14. [The development of a static water/gas separator].

    PubMed

    Zhou, K H; Ai, S K; Lu, X Y; Liu, C L

    2000-10-01

    Objective. To develop a device for separating water from gas in small flow rate under zero "G". Method. Beginning with the study of surface characteristic of materials, a capillary material was developed according to the requirement and the water/gas separator using this single separating material was designed. Result. The water/gas separator worked well in the range of gas flow below 10.0 L/min and water flow below 10.0 ml/min. No gas was found in the separated water and no water was found in the separated gas. Conclusion. The structure of the separator was reasonable and the water/gas separating method using a single separating material was feasible.

  15. KINETICS OF DIRECT OXIDATION OF H2S IN COAL GAS TO ELEMENTAL SULFUR

    SciTech Connect

    K.C. Kwon

    2005-01-01

    The direct oxidation of H{sub 2}S to elemental sulfur in the presence of SO{sub 2} is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H{sub 2}S. This direct oxidation process has the potential to produce a super clean coal gas more economically than both conventional amine-based processes and the hot-gas desulfurization using regenerable metal oxide sorbents followed by Direct Sulfur Recovery Process. The objective of this research is to support the near- and long-term process development efforts to commercialize this direct oxidation technology. The objectives of this research are to measure kinetics of direct oxidation of H{sub 2}S to elemental sulfur in the presence of a simulated coal gas mixture containing SO{sub 2}, H{sub 2}, and moisture, using 160-{micro}m C-500-04 alumina catalyst particles and a micro bubble reactor, and to develop kinetic rate equations and model the direct oxidation process to assist in the design of large-scale plants. This heterogeneous catalytic reaction has gaseous reactants such as H{sub 2}S and SO{sub 2}. However, this heterogeneous catalytic reaction has heterogeneous products such as liquid elemental sulfur and steam. To achieve the above-mentioned objectives, experiments on conversion of hydrogen sulfide into liquid elemental sulfur were carried out for the space time range of 0.059-0.87 seconds at 125-155 C to evaluate effects of reaction temperature, H{sub 2}S concentration, reaction pressure, and catalyst loading on conversion of hydrogen sulfide into liquid elemental sulfur. Simulated coal gas mixtures consist of 62-78 v% hydrogen, 3,000-7,000-ppmv hydrogen sulfide, 1,500-3,500 ppmv sulfur dioxide, and 10 vol % moisture, and nitrogen as remainder. Volumetric feed rates of a simulated coal gas mixture to a micro bubble reactor are 50 cm{sup 3}/min at room temperature and atmospheric pressure. The temperature of the reactor is controlled in an

  16. KINETICS OF DIRECT OXIDATION OF H2S IN COAL GAS TO ELEMENTAL SULFUR

    SciTech Connect

    K.C. Kwon

    2004-01-01

    The direct oxidation of H{sub 2}S to elemental sulfur in the presence of SO{sub 2} is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H{sub 2}S. This direct oxidation process has the potential to produce a super clean coal gas more economically than both conventional amine-based processes and the hot-gas desulfurization using regenerable metal oxide sorbents followed by Direct Sulfur Recovery Process. The objective of this research is to support the near- and long-term process development efforts to commercialize this direct oxidation technology. The objectives of this research are to measure kinetics of direct oxidation of H{sub 2}S to elemental sulfur in the presence of a simulated coal gas mixture containing SO{sub 2}, H{sub 2}, and moisture, using 160-{micro}m C-500-04 alumina catalyst particles and a micro bubble reactor, and to develop kinetic rate equations and model the direct oxidation process to assist in the design of large-scale plants. This heterogeneous catalytic reaction has gaseous reactants such as H{sub 2}S and SO{sub 2}. However, this heterogeneous catalytic reaction has heterogeneous products such as liquid elemental sulfur and steam. To achieve the above-mentioned objectives, experiments on conversion of hydrogen sulfide into liquid elemental sulfur were carried out for the space time range of 1-6 milliseconds at 125-155 C to evaluate effects of reaction temperature, moisture concentration, reaction pressure on conversion of hydrogen sulfide into liquid elemental sulfur. Simulated coal gas mixtures consist of 70 v% hydrogen, 2,500-7,500-ppmv hydrogen sulfide, 1,250-3,750 ppmv sulfur dioxide, and 0-15 vol% moisture, and nitrogen as remainder. Volumetric feed rates of a simulated coal gas mixture to a micro bubble reactor are 100 cm{sup 3}/min at room temperature and atmospheric pressure. The temperature of the reactor is controlled in an oven at 125-155 C. The

  17. Low Metallicity ISM: excess submillimetre emission and CO-free H2 gas

    NASA Astrophysics Data System (ADS)

    Madden, Suzanne C.; Rémy, Aurélie; Galliano, Frédéric; Galametz, Maud; Bendo, George; Cormier, Diane; Lebouteiller, Vianney; Hony, Sacha

    2012-08-01

    The low metallicity interstellar medium of dwarf galaxies gives a different picture in the far infrared(FIR)/submillimetre(submm)wavelengths than the more metal-rich galaxies. Excess emission is often found in the submm beginning at or beyond 500 μm. Even without taking this excess emission into account as a possible dust component, higher dust-to-gas mass ratios (DGR) are often observed compared to that expected from their metallicity for moderately metal-poor galaxies. The Spectral Energy Distributions (SEDs) of the lowest metallicity galaxies, however, give very low dust masses and excessively low values of DGR, inconsistent with the amount of metals expected to be captured into dust if we presume the usual linear relationship holding for all metallicities, including the more metal-rich galaxies. This transition seems to appear near metalllicities of 12 + log(O/H) 8.0 - 8.2. These results rely on accurately quantifying the total molecular gas reservoir, which is uncertain in low metallicity galaxies due to the difficulty in detecting CO(1-0) emission. Dwarf galaxies show an exceptionally high [CII] 158 μm/CO (1-0) ratio which may be indicative of a significant reservoir of `CO-free' molecular gas residing in the photodissociated envelope, and not traced by the small CO cores.

  18. Quantum cascade laser investigations of CH4 and C2H2 interconversion in hydrocarbon/H2 gas mixtures during microwave plasma enhanced chemical vapor deposition of diamond

    NASA Astrophysics Data System (ADS)

    Ma, Jie; Cheesman, Andrew; Ashfold, Michael N. R.; Hay, Kenneth G.; Wright, Stephen; Langford, Nigel; Duxbury, Geoffrey; Mankelevich, Yuri A.

    2009-08-01

    CH4 and C2H2 molecules (and their interconversion) in hydrocarbon/rare gas/H2 gas mixtures in a microwave reactor used for plasma enhanced diamond chemical vapor deposition (CVD) have been investigated by line-of-sight infrared absorption spectroscopy in the wavenumber range of 1276.5-1273.1 cm-1 using a quantum cascade laser spectrometer. Parameters explored include process conditions [pressure, input power, source hydrocarbon, rare gas (Ar or Ne), input gas mixing ratio], height (z) above the substrate, and time (t) after addition of hydrocarbon to a pre-existing Ar/H2 plasma. The line integrated absorptions so obtained have been converted to species number densities by reference to the companion two-dimensional (r ,z) modeling of the CVD reactor described in Mankelevich et al. [J. Appl. Phys. 104, 113304 (2008)]. The gas temperature distribution within the reactor ensures that the measured absorptions are dominated by CH4 and C2H2 molecules in the cool periphery of the reactor. Nonetheless, the measurements prove to be of enormous value in testing, tensioning, and confirming the model predictions. Under standard process conditions, the study confirms that all hydrocarbon source gases investigated (methane, acetylene, ethane, propyne, propane, and butane) are converted into a mixture dominated by CH4 and C2H2. The interconversion between these two species is highly dependent on the local gas temperature and the H atom number density, and thus on position within the reactor. CH4→C2H2 conversion occurs most efficiently in an annular shell around the central plasma (characterized by 1400H2→CH4 is favored in the more distant regions where Tgas<1400 K. Analysis of the multistep interconversion mechanism reveals substantial net consumption of H atoms accompanying the CH4→C2H2 conversion, whereas the reverse C2H2→CH4 process only requires H atoms to drive the reactions; H atoms are not consumed by the overall

  19. Hydrothermal synthesized magnetically separable mesostructured H2Ti3O7/γ-Fe2O3 nanocomposite for organic dye removal via adsorption and its regeneration/reuse through synergistic non-radiation driven H2O2 activation.

    PubMed

    Narayani, Harsha; Jose, Manu; Sriram, K; Shukla, Satyajit

    2017-02-14

    Hydrogen titanate (H2Ti3O7) nanotubes/nanosheets (HTN) are emerging class of adsorbent material which possess unique property of activating hydrogen peroxide (H2O2) to generate the reactive oxygen species (ROS), such as superoxide radical ions (O2(.-)) and hydroxyl radicals (·OH), effective in the decomposition of surface-adsorbed dye. However, HTN are non-magnetic which create hurdle in their effective separation from the treated aqueous solution. To overcome this issue, magnetic nanocomposites (HTNF) composed of HTN and maghemite (γ-Fe2O3) nanoparticles have been processed by subjecting the core-shell magnetic photocatalyst consisting of γ-Fe2O3/silica (SiO2)/titania (TiO2), having varying amounts of TiO2 in the shell to the hydrothermal conditions. HTNF-5 magnetic nanocomposite consisting of 31 wt% H2Ti3O7, typically having nanotube morphology with the highest specific surface area (133 m(2) g(-1)) and pore-volume (0.22 cm(3) g(-1)), exhibits the highest capacity (74 mg g(-1)) for the adsorption of cationic methylene blue (MB) dye from an aqueous solution involving the electrostatic attraction mechanism and pseudo-second-order kinetics. Very fast magnetic separation followed by regeneration of HTNF-5 magnetic nanocomposite has been demonstrated via non-radiation driven H2O2 activation. It has been ascertained for the first time that the underlying mechanism of dye decomposition involves the synergy effect between the constituents of HTNF magnetic nanocomposite.

  20. KINETICS OF DIRECT OXIDATION OF H2S IN COAL GAS TO ELEMENTAL SULFUR

    SciTech Connect

    K.C. Kwon

    2003-01-01

    The direct oxidation of H{sub 2}S to elemental sulfur in the presence of SO{sub 2} is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H{sub 2}S. This direct oxidation process has the potential to produce a super clean coal gas more economically than both conventional amine-based processes and HGD/DSRP. The objective of this research is to support the near- and long-term DOE efforts to commercialize this direct oxidation technology. The objectives of this research are to measure kinetics of direct oxidation of H{sub 2}S to elemental sulfur in the presence of a simulated coal gas mixture containing SO{sub 2}, H{sub 2}, and moisture, using 60-{micro}m C-500-04 alumina catalyst particles and a PFA differential fixed-bed micro reactor, and to develop kinetic rate equations and model the direct oxidation process to assist in the design of large-scale plants. To achieve the above-mentioned objectives, experiments on conversion of hydrogen sulfide into elemental sulfur were carried out for the space time range of 0.01-0.047 seconds at 125-155 C to evaluate effects of reaction temperatures, moisture concentrations, reaction pressures on conversion of hydrogen sulfide into elemental sulfur. Simulated coal gas mixtures consist of 61-89 v% hydrogen, 2,300-9,200-ppmv hydrogen sulfide, 1,600-4,900 ppmv sulfur dioxide, and 2.6-13.7 vol % moisture, and nitrogen as remainder. Volumetric feed rates of a simulated coal gas mixture to the reactor are 100-110 cm{sup 3}/min at room temperature and atmospheric pressure (SCCM). The temperature of the reactor is controlled in an oven at 125-155 C. The pressure of the reactor is maintained at 28-127 psia. The following results were obtained based on experimental data generated from the differential reactor system, and their interpretations, (1) Concentration of moisture and concentrations of both H{sub 2}S and SO{sub 2} appear to affect slightly reaction

  1. Low temperature H2S removal with 3-D structural mesoporous molecular sieves supported ZnO from gas stream.

    PubMed

    Li, L; Sun, T H; Shu, C H; Zhang, H B

    2016-07-05

    A series of 3-dimensional (3-D) structural mesoporous silica materials, SBA-16, MCM-48 and KIT-6, was synthesized and supported with different ZnO loadings (10, 20, 30, and 40 wt%) by the incipient wetness method to evaluate the performances on H2S removal at room temperature. These materials were characterized by N2 adsorption, XRD, and TEM to investigate their textural properties. All the ZnO-loaded adsorbents exhibited the H2S removal capacity of bellow 0.1 ppmv. With the best ZnO loading percentage of 30 wt% on MCM-48 and KIT-6, 20 wt% on SBA-16 according to the results of breakthrough test, further increasing ZnO loading caused the decrease of the adsorption capacity due to the agglomeration of ZnO. Besides, the H2S adsorption capacities of the supports materials varied in the order of KIT-6>MCM-48>SBA-16, which was influenced primarily by their pore volume and pore size. With the largest pores in these 3-D arrangement materials, KIT-6 showed the best performance of supported material for ZnO, due to its retained superior physical properties as well as large pore diameter to allow faster gas-solid interaction and huge pore volume to disperse ZnO on the surface of it.

  2. Muonium Addition Reactions and Kinetic Isotope Effects in the Gas Phase: k∞ Rate Constants for Mu + C2H2.

    PubMed

    Arseneau, Donald J; Garner, David M; Reid, Ivan D; Fleming, Donald G

    2015-07-16

    The kinetics of the addition reaction of muonium (Mu) to acetylene have been studied in the gas phase at N2 moderator pressures mainly from ∼800 to 1000 Torr and over the temperature range from 168 to 446 K, but also down to 200 Torr at 168 K and over a much higher range of pressures, from 10 to 44 bar at 295 K, demonstrating pressure-independent rate constants, kMu(T). Even at 200 Torr moderator pressure, the kinetics for Mu + C2H2 addition behave as if effectively in the high-pressure limit, giving k∞ = kMu due to depolarization of the muon spin in the MuC2H2 radical formed in the addition step. The rate constants kMu(T) exhibit modest Arrhenius curvature over the range of measured temperatures. Comparisons with data and with calculations for the corresponding H(D) + C2H2 addition reactions reveal a much faster rate for the Mu reaction at the lowest temperatures, by 2 orders of magnitude, in accord with the propensity of Mu to undergo quantum tunneling. Moreover, isotopic atom exchange, which contributes in a major way to the analogous D atom reaction, forming C2HD + H, is expected to be unimportant in the case of Mu addition, a consequence of the much higher zero-point energy and hence weaker C-Mu bond that would form, meaning that the present report of the Mu + C2H2 reaction is effectively the only experimental study of kinetic isotope effects in the high-pressure limit for H-atom addition to acetylene.

  3. Theoretical study of the gas-phase reactions of iodine atoms ((2)P(3/2)) with H(2), H(2)O, HI, and OH.

    PubMed

    Canneaux, Sébastien; Xerri, Bertrand; Louis, Florent; Cantrel, Laurent

    2010-09-02

    The rate constants of the reactions of iodine atoms with H(2), H(2)O, HI, and OH have been estimated using 39, 21, 13, and 39 different levels of theory, respectively, and have been compared to the available literature values over the temperature range of 250-2500 K. The aim of this methodological work is to demonstrate that standard theoretical methods are adequate to obtain quantitative rate constants for the reactions involving iodine-containing species. Geometry optimizations and vibrational frequency calculations are performed using three methods (MP2, MPW1K, and BHandHLYP) combined with three basis sets (cc-pVTZ, cc-pVQZ, and 6-311G(d,p)). Single-point energy calculations are performed with the highly correlated ab initio coupled cluster method in the space of single, double, and triple (pertubatively) electron excitations CCSD(T) using the cc-pVnZ (n = T, Q, and 5), aug-cc-pVnZ (n = T, Q, and 5), 6-311G(d,p), 6-311+G(3df,2p), and 6-311++G(3df,3pd) basis sets. Canonical transition state theory with a simple Wigner tunneling correction is used to predict the rate constants as a function of temperature. CCSD(T)/cc-pVnZ//MP2/cc-pVTZ (n = T and Q), CCSD(T)/6-311+G(3df,2p)//MP2/6-311G(d,p), and CCSD(T)/6-311++G(3df,3pd)//MP2/6-311G(d,p) levels of theory provide accurate kinetic rate constants when compared to available literature data. The use of the CCSD(T)/cc-pVQZ//MP2/cc-pVTZ and CCSD(T)/6-311++G(3df,3pd) levels of theory allows one to obtain a better agreement with the literature data for all reactions with the exception of the I + H(2) reaction R(1) . This computational procedure has been also used to predict rate constants for some reactions where no available experimental data exist. The use of quantum chemistry tools could be therefore extended to other elements and next applied to develop kinetic networks involving various fission products, steam, and hydrogen in the absence of literature data. The final objective is to implement the kinetics of gaseous

  4. Immobilized fluid membranes for gas separation

    SciTech Connect

    Liu, Wei; Canfield, Nathan L; Zhang, Jian; Li, Xiaohong Shari; Zhang, Jiguang

    2014-03-18

    Provided herein are immobilized liquid membranes for gas separation, methods of preparing such membranes and uses thereof. In one example, the immobilized membrane includes a porous metallic host matrix and an immobilized liquid fluid (such as a silicone oil) that is immobilized within one or more pores included within the porous metallic host matrix. The immobilized liquid membrane is capable of selective permeation of one type of molecule (such as oxygen) over another type of molecule (such as water). In some examples, the selective membrane is incorporated into a device to supply oxygen from ambient air to the device for electrochemical reactions, and at the same time, to block water penetration and electrolyte loss from the device.

  5. Multidimensional gas chromatography beyond simple volatiles separation.

    PubMed

    Chin, Sung-Tong; Marriott, Philip J

    2014-08-18

    Multidimensional separation in gas chromatography (MDGC) plays an important role in chemical analysis. This review presents selected literature on MDGC development and examples of the range of functionality reported for MDGC methods over the past 2 decades. With the most obvious advantage of providing much greater capacity for resolving constituents of a sample, MDGC extends analytical efficiency to a more substantial molecular coverage, combined with operational flexibility. But by judicious choice of implementation method, important chemical information relating to the sample, its components, potentially physico-chemical properties, and improved capacity for absolute identification may be realised. Sample-to-sample comparison is improved, and sample characterisation is facilitated especially when MDGC is combined with the informing power of modern mass spectrometry. Innovative MDGC arrangements allow high resolution coupled with spectroscopy and alternative bioassays, and delivers molecular elucidation in ways that are beyond just simple analysis of volatiles.

  6. TUNABLE COMPOSITE MEMBRANES FOR GAS SEPARATIONS

    SciTech Connect

    J.P. Ferraris; K.J. Balkus, Jr.; I.H. Musselman

    1999-01-01

    Poly 2-(3-thienyl)ethylacetate (PAET) was synthesized and solution cast as thin films to form dense membranes. These membranes are mechanically robust and are redox active, holding out promise as gas separation materials. The permeability properties of PAET membranes were evaluated for N{sub 2} (0.048 {+-} 0.008 Barrers), O{sub 2} (0.24 {+-} 0.02 Barrers), CH{sub 4} (0.081 {+-} 0.005 Barrers), and CO{sub 2} (1.4 {+-} 0.1 Barrers). The corresponding selectivity values ({alpha}) were: O{sub 2}/N{sub 2} = 5.1, CO{sub 2}/N{sub 2} = 29, and CO{sub 2}/CH{sub 4} = 18.

  7. Evaluation and Characterization of Membranes for H2SO4/Water and I2/HI/H2O Water Separation and Hydrogen Permeation for the S-I Cycle

    SciTech Connect

    Frederick R. Stewart

    2006-10-01

    In this report are the findings into three membrane separation studies for potential application to the Sulfur-Iodine (S-I) thermochemical cycle. The first is the removal of water from hydriodic acid/iodine mixtures. In the S-I cycle, iodine is added to the product of the Bunsen reaction to facilitate the separation of sulfuric acid (H2SO4) from hydriodic acid (HI). The amount of iodine can be as high as 83% of the overall mass load of the Bunsen product stream, which potentially introduces a large burden on the cycle’s efficiency. Removal of water from the HI and iodine mixture would substantially reduce the amount of required additional iodine. In this work, performance data for Nafion® and sulfonated poly (ether ether ketone) (SPEEK) membranes is shown.

  8. Gas-liquid separator and method of operation

    DOEpatents

    Soloveichik, Grigorii Lev; Whitt, David Brandon

    2009-07-14

    A system for gas-liquid separation in electrolysis processes is provided. The system includes a first compartment having a liquid carrier including a first gas therein and a second compartment having the liquid carrier including a second gas therein. The system also includes a gas-liquid separator fluidically coupled to the first and second compartments for separating the liquid carrier from the first and second gases.

  9. Numerical study of an ArH2 gas mixture flowing inside and outside a dc plasma torch

    NASA Astrophysics Data System (ADS)

    Eichert, P.; Imbert, M.; Coddet, C.

    1998-12-01

    The flow of gas mixtures in a dc plasma torch is studied using the CFD PHOENICS (CFD PHOENICS, Berkeley, CA) code. In the model, the cold gas mixture (300 K), initially constituted of 85 vol% Ar and 15 vol% H, is introduced into a power input zone where it takes energy and is ejected in the surrounding atmosphere at constant pressure (105 Pa). The flow is assumed to be in chemical equilibrium. Equations of mass, momentum, and energy are discretized using a control-volume method. The turbulent flow is modeled by a k-ɛ two-equations model for the turbulent kinetic energy and its dissipation rate. Finally, the algebraic coupling equations set is solved by means of the SIMPLEST algorithm, implemented into the CFD code, using a hybrid interpolation scheme. Results concern the effect of the torch power on the ArH2 flow. The phenomenon is analyzed through the evolution of velocity and temperature inside and outside the torch. From these calculations, the effect of ambient gas entrainment by the jet is emphasized and a comparison of the level of entrained gas is made with experimental data.

  10. Remote sensing of high temperature H2O CO2 CO mixture with a correlated k-distribution fictitious gas method and the single-mixture gas assumption

    NASA Astrophysics Data System (ADS)

    Caliot, C.; Le Maoult, Y.; El Hafi, M.; Flamant, G.

    2006-11-01

    Infrared spectra of high temperature H2O CO2 CO mixtures are calculated using narrow band models in order to simulate hot jet signature at long distance. The correlated k-distribution with fictitious gas (CKFG) approach generally gives accurate data in such situations (especially for long atmospheric paths) but results in long computation time in cases involving mixtures of gases. This time may be reduced if the mixture is treated as a single gas (single-mixture gas assumption, SMG). Thus the lines of the single-mixture gas are assigned to the fictitious gases. In this study, the accuracy of two narrow band models is evaluated. The first narrow band model considers one single-mixture gas and no fictitious gas (CK-SMG) whereas the second model accounts for one single-mixture gas and three fictitious gases (CKFG-SMG). Both narrow band models are compared with reference spectra calculated with a line-by-line (LBL) approach. As expected, the narrow band accuracy is improved by the fictitious gas (FG) assumption particularly when long atmospheric paths are involved. Concerning the SMG assumption, it may lead to an underestimation of about 10% depending on the variation of the gas mixture composition ratio. Nevertheless, in most of realistic situations the SMG assumption results in negligible errors and may be used for remote sensing of plume signature.

  11. Computational identification of a metal organic framework for high selectivity membrane-based CO2/CH4 separations: Cu(hfipbb)(H2hfipbb)0.5.

    PubMed

    Watanabe, Taku; Keskin, Seda; Nair, Sankar; Sholl, David S

    2009-12-28

    The identification of membrane materials with high selectivity for CO(2)/CH(4) mixtures could revolutionize this industrially important separation. We predict using computational methods that a metal organic framework (MOF), Cu(hfipbb)(H(2)hfipbb)(0.5), has unprecedented selectivity for membrane-based separation of CO(2)/CH(4) mixtures. Our calculations combine molecular dynamics, transition state theory, and plane wave DFT calculations to assess the importance of framework flexibility in the MOF during molecular diffusion. This combination of methods should also make it possible to identify other MOFs with attractive properties for kinetic separations.

  12. Dopant-assisted negative photoionization Ion mobility spectrometry coupled with on-line cooling inlet for real-time monitoring H2S concentration in sewer gas.

    PubMed

    Peng, Liying; Jiang, Dandan; Wang, Zhenxin; Hua, Lei; Li, Haiyang

    2016-06-01

    Malodorous hydrogen sulfide (H2S) gas often exists in the sewer system and associates with the problems of releasing the dangerous odor to the atmosphere and causing sewer pipe to be corroded. A simple method is in demand for real-time measuring H2S level in the sewer gas. In this paper, an innovated method based on dopant-assisted negative photoionization ion mobility spectrometry (DANP-IMS) with on-line semiconductor cooling inlet was put forward and successfully applied for the real-time measurement of H2S in sewer gas. The influence of moisture was effectively reduced via an on-line cooling method and a non-equilibrium dilution with drift gas. The limits of quantitation for the H2S in ≥60% relative humidity air could be obtained at ≤79.0ng L(-1) with linear ranges of 129-2064ng L(-1). The H2S concentration in a sewer manhole was successfully determined while its product ions were identified by an ion-mobility time-of-fight mass spectrometry. Finally, the correlation between sewer H2S concentration and the daily routines and habits of residents was investigated through hourly or real-time monitoring the variation of sewer H2S in manholes, indicating the power of this DANP-IMS method in assessing the H2S concentration in sewer system.

  13. High H2O-resistance CaO-MnOx/MSU-H sorbents for hot coal gas desulfurization.

    PubMed

    Xia, Hong; Liu, Bingsi

    2017-02-15

    A series of xMnyCa/MSU-H sorbents with various Mn/Ca molar ratio were first designed and synthesized with a sol-gel method. The desulfurization performance of the new sorbent was investigated at 600-800°C in hot coal gas. 90Mn10Ca/MSU-H exhibited better desulfurization performance at 750°C with a breakthrough sulfur capacity (BSC) of 18.69g S/100g sorbent compared to other supported Mn-based sorbents (13.2g S/100g sorbent) in similar desulfurization condition, and strong durability in multiple sulfidation-regeneration cycles using oxidation/reduction regeneration method which resolved the scientific issue of that CaSO4 is hardly decomposed to CaO. The introduction of Ca species effectively promoted the dispersion of active constituents, which improved the desulfurization activity. More importantly, 90Mn10Ca/MSU-H showed excellent H2O-resistance ability due to the fact that CaO enhanced the sorption of H2O. Moreover, the utilization of MSU-H with large pore size and excellent thermal stability effectively assured fast mass-transfer and confined the migration of active particles, which led to long lifetime stability of sorbents.

  14. Implementation of a quantum cascade laser-based gas sensor prototype for sub-ppmv H2S measurements in a petrochemical process gas stream.

    PubMed

    Moser, Harald; Pölz, Walter; Waclawek, Johannes Paul; Ofner, Johannes; Lendl, Bernhard

    2017-01-01

    The implementation of a sensitive and selective as well as industrial fit gas sensor prototype based on wavelength modulation spectroscopy with second harmonic detection (2f-WMS) employing an 8-μm continuous-wave distributed feedback quantum cascade laser (CW-DFB-QCL) for monitoring hydrogen sulfide (H2S) at sub-ppm levels is reported. Regarding the applicability for analytical and industrial process purposes aimed at petrochemical environments, a synthetic methane (CH4) matrix of up to 1000 ppmv together with a varying H2S content was chosen as the model environment for the laboratory-based performance evaluation performed at TU Wien. A noise-equivalent absorption sensitivity (NEAS) for H2S targeting the absorption line at 1247.2 cm(-1) was found to be 8.419 × 10(-10) cm(-1) Hz(-1/2), and a limit of detection (LOD) of 150 ppbv H2S could be achieved. The sensor prototype was then deployed for on-site measurements at the petrochemical research hydrogenation platform of the industrial partner OMV AG. In order to meet the company's on-site safety regulations, the H2S sensor platform was installed in an industry rack and equipped with the required safety infrastructure for protected operation in hazardous and explosive environments. The work reports the suitability of the sensor prototype for simultaneous monitoring of H2S and CH4 content in the process streams of a research hydrodesulfurization (HDS) unit. Concentration readings were obtained every 15 s and revealed process dynamics not observed previously.

  15. Multiwalled carbon nanotubes mass-produced by dc arc discharge in He-H2 gas mixture

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Guo, Y.; Inoue, S.; Zhao, X.; Ohkohchi, M.; Ando, Y.

    2006-04-01

    Uniform cathode deposits (longer than 15 mm), containing multiwalled carbon nanotubes (MWNTs) inside, were produced by dc arc discharge evaporation with a computer-controlled feeder of a pure-carbon electrode without a metal catalyst in a He-H2 gas mixture. The purification of MWNTs was carried out to remove amorphous carbon and carbon nanoparticles. High-resolution transmission electron microscopy observations and Raman scattering studies show that the MWNTs possess a high crystallinity and a mean outermost diameter of ˜ ˜10 nm. It has been confirmed that the current density in the electron field emission from a purified MWNT mat can reach 77.92 mA/cm2, indicating that the purified MWNTs are a promising candidate electron source in a super high-luminance light-source tube or a miniature X-ray source.

  16. Optimisation of the Fischer-Tropsch process using zeolites for tail gas separation.

    PubMed

    Perez-Carbajo, J; Gómez-Álvarez, P; Bueno-Perez, R; Merkling, P J; Calero, S

    2014-03-28

    This work is aimed at optimizing a Fischer-Tropsch Gas To Liquid (GTL) process by recycling compounds of the expelled gas mixture using zeolites for the separation. To that end, we have performed a computational study on four structures widely used in industry. A range of Si/Al ratios have been explored and the effects of their distribution assessed. The ability of the considered force fields and molecular models to reproduce experimental results has been widely proved in previously reported studies. Since this tail gas is formed by a five-component mixture, namely carbon dioxide, methane, carbon monoxide, nitrogen and hydrogen, molecular simulations present clear advantages over experiments. In addition, the viability of the Ideal Adsorption Solution Theory (IAST) has been evaluated to easily handle further separation steps. On the basis of the obtained results, we provide a separation scheme to perform sequentially the separation of CO2, CH4, CO, N2 and H2.

  17. Sequential bond energies and barrier heights for the water loss and charge separation dissociation pathways of Cd2+(H2O)n, n = 3-11

    NASA Astrophysics Data System (ADS)

    Cooper, Theresa E.; Armentrout, P. B.

    2011-03-01

    The bond dissociation energies for losing one water from Cd2+(H2O)n complexes, n = 3-11, are measured using threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer coupled with a thermal electrospray ionization source. Kinetic energy dependent cross sections are obtained for n = 4-11 complexes and analyzed to yield 0 K threshold measurements for loss of one, two, and three water ligands after accounting for multiple collisions, kinetic shifts, and energy distributions. The threshold measurements are converted from 0 to 298 K values to give the hydration enthalpies and free energies for sequentially losing one water from each complex. Theoretical geometry optimizations and single point energy calculations are performed on reactant and product complexes using several levels of theory and basis sets to obtain thermochemistry for comparison to experiment. The charge separation process, Cd2+(H2O)n → CdOH+(H2O)m + H+(H2O)n-m-1, is also observed for n = 4 and 5 and the competition between this process and water loss is analyzed. Rate-limiting transition states for the charge separation process at n = 3-6 are calculated and compared to experimental threshold measurements resulting in the conclusion that the critical size for this dissociation pathway of hydrated cadmium is ncrit = 4.

  18. Numerical modeling of gas mixing and bio-chemical transformations during underground hydrogen storage within the project H2STORE

    NASA Astrophysics Data System (ADS)

    Hagemann, B.; Feldmann, F.; Panfilov, M.; Ganzer, L.

    2015-12-01

    The change from fossil to renewable energy sources is demanding an increasing amount of storage capacities for electrical energy. A promising technological solution is the storage of hydrogen in the subsurface. Hydrogen can be produced by electrolysis using excessive electrical energy and subsequently converted back into electricity by fuel cells or engine generators. The development of this technology starts with adding small amounts of hydrogen to the high pressure natural gas grid and continues with the creation of pure underground hydrogen storages. The feasibility of hydrogen storage in depleted gas reservoirs is investigated in the lighthouse project H2STORE financed by the German Ministry for Education and Research. The joint research project has project members from the University of Jena, the Clausthal University of Technology, the GFZ Potsdam and the French National Center for Scientic Research in Nancy. The six sub projects are based on laboratory experiments, numerical simulations and analytical work which cover the investigation of mineralogical, geochemical, physio-chemical, sedimentological, microbiological and gas mixing processes in reservoir and cap rocks. The focus in this presentation is on the numerical modeling of underground hydrogen storage. A mathematical model was developed which describes the involved coupled hydrodynamic and microbiological effects. Thereby, the bio-chemical reaction rates depend on the kinetics of microbial growth which is induced by the injection of hydrogen. The model has been numerically implemented on the basis of the open source code DuMuX. A field case study based on a real German gas reservoir was performed to investigate the mixing of hydrogen with residual gases and to discover the consequences of bio-chemical reactions.

  19. Device for separation of vortex gas-dynamic energy

    NASA Astrophysics Data System (ADS)

    Leontiev, A. I.; Burtsev, S. A.

    2015-10-01

    A device for separation of vortex gas-dynamic energy, which combines the mechanism of separation of vortex energy used in the Ranque-Hilsch tubes and the mechanism of separation of gas-dynamic energy, is proposed for supersonic flows. A method of calculation of this device is developed. A comparison is made that showed that, when working with natural gas, the cooling depth of half of the mass flow rate proves to be 1.3 times higher than that for the vortex tube and three times higher than that for the device for separation of the gas-dynamic energy.

  20. Photoionization-induced water migration in the amide group of trans-acetanilide-(H2O)1 in the gas phase.

    PubMed

    Sakota, Kenji; Harada, Satoshi; Shimazaki, Yuiga; Sekiya, Hiroshi

    2011-02-10

    IR-dip spectra of trans-acetanilide-water 1:1 cluster, AA-(H(2)O)(1), have been measured for the S(0) and D(0) state in the gas phase. Two structural isomers, where a water molecule binds to the NH group or the CO group of AA, AA(NH)-(H(2)O)(1) and AA(CO)-(H(2)O)(1), are identified in the S(0) state. One-color resonance-enhanced two-photon ionization, (1 + 1) RE2PI, of AA(NH)-(H(2)O)(1) via the S(1)-S(0) origin generates [AA(NH)-(H(2)O)(1)](+) in the D(0) state, however, photoionization of [AA(CO)-(H(2)O)(1)] does not produce [AA(CO)-(H(2)O)(1)](+), leading to [AA(NH)-(H(2)O)(1)](+). This observation explicitly indicates that the water molecule in [AA-(H(2)O)(1)](+) migrates from the CO group to the NH group in the D(0) state. The reorganization of the charge distribution from the neutral to the D(0) state of AA induces the repulsive force between the water molecule and the CO group of AA(+), which is the trigger of the water migration in [AA-(H(2)O)(1)](+).

  1. Oil/gas collector/separator for underwater oil leaks

    SciTech Connect

    Henning, C.D.

    1992-12-31

    This invention is comprised of an oil/gas collector/separator for recovery of oil leaking, for example, from an offshore or underwater oil well. The separator is floated over the point of the leak and tethered in place so as to receive oil/gas floating, or forced under pressure, toward the water surface from either a broken or leaking oil well casing, line, or sunken ship. The separator is provided with a downwardly extending skirt to contain the oil/gas which floats or is forced upward into a dome wherein the gas is separated from the oil/water, with the gas being flared (burned) at the top of the dome, and the oil is separated from water and pumped to a point of use. Since the density of oil is less than that of water it can be easily separated from any water entering the dome.

  2. Oil/gas collector/separator for underwater oil leaks

    DOEpatents

    Henning, Carl D.

    1993-01-01

    An oil/gas collector/separator for recovery of oil leaking, for example, from an offshore or underwater oil well. The separator is floated over the point of the leak and tethered in place so as to receive oil/gas floating, or forced under pressure, toward the water surface from either a broken or leaking oil well casing, line, or sunken ship. The separator is provided with a downwardly extending skirt to contain the oil/gas which floats or is forced upward into a dome wherein the gas is separated from the oil/water, with the gas being flared (burned) at the top of the dome, and the oil is separated from water and pumped to a point of use. Since the density of oil is less than that of water it can be easily separated from any water entering the dome.

  3. Dynamics of gas-driven eruptions: Experimental simulations using CO2-H2O-polymer system

    NASA Astrophysics Data System (ADS)

    Zhang, Youxue; Sturtevant, B.; Stolper, E. M.

    1997-02-01

    We report exploratory experiments simulating gas-driven eruptions using the CO2-H2O system at room temperature as an analog of natural eruptive systems. The experimental apparatus consists of a test cell and a large tank. Initially, up to 1.0 wt% of CO2 is dissolved in liquid water under a pressure of up to 735 kPa in the test cell. The experiment is initiated by suddenly reducing the pressure of the test cell to a typical tank pressure of 10 kPa. The following are the main results: (1) The style of the process depends on the decompression ratio. There is a threshold decompression ratio above which rapid eruption occurs. (2) During rapid eruption, there is always fragmentation at the liquid-vapor interface. Fragmentation may also occur in the flow interior. (3) Initially, the top of the erupting column ascends at a constant acceleration (instead of constant velocity). (4) Average bubble radius grows as t2/3. (5) When viscosity is 20 times that of pure water or greater, a static foam may be stable after expansion to 97% vesicularity. The experiments provide several insights into natural gas-driven eruptions, including (1) the interplay between bubble growth and ascent of the erupting column must be considered for realistic modeling of bubble growth during gas-driven eruptions, (2) buoyant rise of the bubbly magma is not necessary during an explosive volcanic eruption, and (3) CO2-driven limnic eruptions can be explosive. The violence increases with the initial CO2 content dissolved in water.

  4. Synthesis and characterization of mixed matrix membranes for gas separation

    NASA Astrophysics Data System (ADS)

    Zhang, Yanfeng

    2007-12-01

    Mixed-matrix membranes were prepared from Matrimid RTM and mesoporous ZSM-5 nanoparticles containing crystalline ZSM-5. The mesoporous ZSM-5 has both micropores (0.54 nm) and mesopores (2.7 nm), which were confirmed by XRD, nitrogen adsorption, and TEM. The Young's moduli and glass transition temperatures of mixed-matrix membranes are higher than those of pure MatrimidRTM membranes, suggesting that the polymer chains may penetrate into the mesopores. The ideal selectivity for H2/N2 separation increased from 79.6 for pure Matrimid RTM to 143 at 10% loading, while the selectivity of O2/N 2 increased from 6.6 for pure MatrimidRTM to 10.4 at 20% loading. The ideal H2/CH4 separation factor increased from 83.3 to 169 at 20% loading. The results suggest that the mesopores of the ZSM-5 material can provide good interfacial contact between the nanoparticles and the polymer, since the polymer chains can penetrate into the mesopores. The micropores of ZSM-5 crystals can provide size and shape selectivity. A carbon aerogel was prepared by carbonizing a resorcinol-formaldehyde polymer gel at 800°C. Nitrogen adsorption shows the obtained carbon aerogel has both micropores (0.54 nm) and mesopores (2.14 nm). Zeolite A and zeolite Y nanocrystals were grown in the mesopores of the carbon aerogel, resulting in carbon aerogel-zeolite composites. TEM confirmed the existence of nanosize zeolite crystals in the carbon aerogel matrix. Higher selectivity for the CO2/CH4, O2/N2 and H2/N 2 separation were obtained for carbon aerogel-zeolite, carbon aerogel-zeolite-Matrimid RTM membranes. The small pore diameter of zeolite A and the affinity between the CO2 and zeolite crystals make it perfect for CO 2/CH4 separation. Short single-walled carbon nanotubes (SWNT) functionalized with carboxylic acid groups were made and incorporated into MatrimidRTM to form mixed-matrix membranes. SEM images of mixed-matrix membranes cross-sections showed good dispersion and interfacial contact. Pure gas

  5. Mass-independent fractionation of oxygen isotopes during H2O2 formation by gas-phase discharge from water vapour

    NASA Astrophysics Data System (ADS)

    Velivetskaya, Tatiana A.; Ignatiev, Alexander V.; Budnitskiy, Sergey Y.; Yakovenko, Victoria V.; Vysotskiy, Sergey V.

    2016-11-01

    Hydrogen peroxide is an important atmospheric component involved in various gas-phase and aqueous-phase transformation processes in the Earth's atmosphere. A study of mass-independent 17O anomalies in H2O2 can provide additional insights into the chemistry of the modern atmosphere and, possibly, of the ancient atmosphere. Here, we report the results of laboratory experiments to study the fractionation of three oxygen isotopes (16O, 17O, and 18O) during H2O2 formation from products of water vapour dissociation. The experiments were carried out by passing an electrical discharge through a gaseous mixture of helium and water at atmospheric pressure. The effect of the presence of O2 in the gas mixture on the isotopic composition of H2O2 was also investigated. All of the experiments showed that H2O2 produced under two different conditions (with or without O2 added in the gas mixtures) was mass-independently fractionated (MIF). We found a positive MIF signal (∼1.4‰) in the no-O2 added experiments, and this signal increased to ∼2.5‰ once O2 was added (1.6% mixing ratio). We suggest that if O2 concentrations are very low, the hydroxyl radical recombination reaction is the dominant pathway for H2O2 formation and is the source of MIF in H2O2. Although H2O2 formation via a hydroxyl radical recombination process is limited in the modern atmosphere, it would be possible in the Archean atmosphere when O2 was a trace constituent, and H2O2 would be mass-independently fractionated. The anomalous 17O excess, which was observed in H2O2 produced by spark discharge experiments, may provide useful information about the radical chemistry of the ancient atmosphere and the role of H2O2 in maintaining and controlling the atmospheric composition.

  6. Stable hydrogen isotopic analysis of nanomolar molecular hydrogen by automatic multi-step gas chromatographic separation.

    PubMed

    Komatsu, Daisuke D; Tsunogai, Urumu; Kamimura, Kanae; Konno, Uta; Ishimura, Toyoho; Nakagawa, Fumiko

    2011-11-15

    We have developed a new automated analytical system that employs a continuous flow isotope ratio mass spectrometer to determine the stable hydrogen isotopic composition (δD) of nanomolar quantities of molecular hydrogen (H(2)) in an air sample. This method improves previous methods to attain simpler and lower-cost analyses, especially by avoiding the use of expensive or special devices, such as a Toepler pump, a cryogenic refrigerator, and a special evacuation system to keep the temperature of a coolant under reduced pressure. Instead, the system allows H(2) purification from the air matrix via automatic multi-step gas chromatographic separation using the coolants of both liquid nitrogen (77 K) and liquid nitrogen + ethanol (158 K) under 1 atm pressure. The analytical precision of the δD determination using the developed method was better than 4‰ for >5 nmol injections (250 mL STP for 500 ppbv air sample) and better than 15‰ for 1 nmol injections, regardless of the δD value, within 1 h for one sample analysis. Using the developed system, the δD values of H(2) can be quantified for atmospheric samples as well as samples of representative sources and sinks including those containing small quantities of H(2) , such as H(2) in soil pores or aqueous environments, for which there is currently little δD data available. As an example of such trace H(2) analyses, we report here the isotope fractionations during H(2) uptake by soils in a static chamber. The δD values of H(2) in these H(2)-depleted environments can be useful in constraining the budgets of atmospheric H(2) by applying an isotope mass balance model.

  7. Oil/gas separator for installation at burning wells

    DOEpatents

    Alonso, Carol T.; Bender, Donald A.; Bowman, Barry R.; Burnham, Alan K.; Chesnut, Dwayne A.; Comfort, III, William J.; Guymon, Lloyd G.; Henning, Carl D.; Pedersen, Knud B.; Sefcik, Joseph A.; Smith, Joseph A.; Strauch, Mark S.

    1993-01-01

    An oil/gas separator is disclosed that can be utilized to return the burning wells in Kuwait to production. Advantageously, a crane is used to install the separator at a safe distance from the well. The gas from the well is burned off at the site, and the oil is immediately pumped into Kuwait's oil gathering system. Diverters inside the separator prevent the oil jet coming out of the well from reaching the top vents where the gas is burned. The oil falls back down, and is pumped from an annular oil catcher at the bottom of the separator, or from the concrete cellar surrounding the well.

  8. Oil/gas separator for installation at burning wells

    DOEpatents

    Alonso, C.T.; Bender, D.A.; Bowman, B.R.; Burnham, A.K.; Chesnut, D.A.; Comfort, W.J. III; Guymon, L.G.; Henning, C.D.; Pedersen, K.B.; Sefcik, J.A.; Smith, J.A.; Strauch, M.S.

    1993-03-09

    An oil/gas separator is disclosed that can be utilized to return the burning wells in Kuwait to production. Advantageously, a crane is used to install the separator at a safe distance from the well. The gas from the well is burned off at the site, and the oil is immediately pumped into Kuwait's oil gathering system. Diverters inside the separator prevent the oil jet coming out of the well from reaching the top vents where the gas is burned. The oil falls back down, and is pumped from an annular oil catcher at the bottom of the separator, or from the concrete cellar surrounding the well.

  9. Improved sensitivity and selectivity of pristine zinc oxide nanostructures to H2S gas: Detailed study on the synthesis reaction time

    NASA Astrophysics Data System (ADS)

    Motaung, David E.; Mhlongo, Gugu H.; Bolokang, Amogelang S.; Dhonge, Baban P.; Swart, Hendrik C.; Sinha Ray, Suprakas

    2016-11-01

    The gas sensing properties of ZnO nanostructures synthesized at various reaction times are reported in this study. The response of ZnO nanostructures to H2, NH3, H2S and NO2 gases was investigated at different operating temperatures and gas concentrations. Surface morphology analyses showed that the geometry of the nanostructures transforms with the synthesis reaction time. Topography analyses demonstrated a surface roughness of approximately 68.25, 70.31, 74.75 nm for the samples synthesized for 24, 48 and 72 h, respectively. The dependence of the morphology on the H2, NH3, NO2 and H2S gas sensing performance was observed. The alteration of the nanostructures diameter/geometry demonstrated a change in both the magnitude and temperature of the maximum sensor response. The 72 h ZnO sensing material revealed improved response and higher sensitivity and selectivity to H2S gas, while the 24 h sensing material revealed enhanced response and selectivity to NO2 gas at 300 °C. Moreover, the 72 h sensing material exhibited a higher sensitivity of 144.22 ppm-1 at 300 °C. These findings disclosed that by varying the synthesis reaction time, the sensing properties, such as the response, sensitivity and selectivity of the ZnO nanostructures could be tuned.

  10. Kinetics of thermal reaction HOCl ⇄ H(2 S) + OCl( X 2Π i ) in gas phase

    NASA Astrophysics Data System (ADS)

    Begović, N.; Marković, Z.; Anić, S.

    2011-12-01

    The kinetics of gas reaction HOCl\\underset{{k_r }}{overset{{k_f }}{longleftrightarrow}}H(^2 S) + OCl(X^2 Pi _i ) was analyzed by the MP4 method. In the temperature range of 100-373 K the rate constants k f and k r and equilibrium constant K were changed from 1.10 × 10-220 to 1.17 × 10-52 s-1, from 2.89 × 10-16 to 1.68 × 10-5s-1 and from 3.80 × 10-205 to 6.96 × 10-48 respectively. In the above temperature range, the activation energy of the forward reaction ( E f) is 105.05 kcal/mol. In the same temperature interval there are two kinetic domains for the reverse reaction with activation energies ( E r1 = 5.53 kcal/mol when T is 100-273 K and E r2 = 14.50 kcal/mol when T is 273-373 K, respectively.

  11. Water deuteration and ortho-to-para nuclear spin ratio of H2 in molecular clouds formed via the accumulation of H I gas

    NASA Astrophysics Data System (ADS)

    Furuya, K.; Aikawa, Y.; Hincelin, U.; Hassel, G. E.; Bergin, E. A.; Vasyunin, A. I.; Herbst, E.

    2015-12-01

    We investigate the water deuteration ratio and ortho-to-para nuclear spin ratio of H2 (OPR(H2)) during the formation and early evolution of a molecular cloud, following the scenario that accretion flows sweep and accumulate H i gas to form molecular clouds. We follow the physical evolution of post-shock materials using a one-dimensional shock model, combined with post-processing gas-ice chemistry simulations. This approach allows us to study the evolution of the OPR(H2) and water deuteration ratio without an arbitrary assumption of the initial molecular abundances, including the initial OPR(H2). When the conversion of hydrogen into H2 is almost complete the OPR(H2) is already much smaller than the statistical value of three because of the spin conversion in the gas phase. As the gas accumulates, the OPR(H2) decreases in a non-equilibrium manner. We find that water ice can be deuterium-poor at the end of its main formation stage in the cloud, compared to water vapor observed in the vicinity of low-mass protostars where water ice is sublimated. If this is the case, the enrichment of deuterium in water should mostly occur at somewhat later evolutionary stages of star formation, i.e., cold prestellar/protostellar cores. The main mechanism to suppress water ice deuteration in the cloud is the cycle of photodissociation and reformation of water ice, which efficiently removes deuterium from water ice chemistry. The removal efficiency depends on the main formation pathway of water ice. The OPR(H2) plays a minor role in water ice deuteration at the main formation stage of water ice. Appendices are available in electronic form at http://www.aanda.org

  12. Herschel Observations of EXtra-Ordinary Sources: H2S as a Probe of Dense Gas and Possibly Hidden Luminosity Toward the Orion KL Hot Core

    NASA Astrophysics Data System (ADS)

    Crockett, N. R.; Bergin, E. A.; Neill, J. L.; Black, J. H.; Blake, G. A.; Kleshcheva, M.

    2014-02-01

    We present Herschel/HIFI observations of the light hydride H2S obtained from the full spectral scan of the Orion Kleinmann-Low nebula (Orion KL) taken as part of the Herschel Observations of EXtra-Ordinary Sources GT (guaranteed time) key program. In total, we observe 52, 24, and 8 unblended or slightly blended features from H2 32S, H2 34S, and H2 33S, respectively. We only analyze emission from the so-called hot core, but emission from the plateau, extended ridge, and/or compact ridge are also detected. Rotation diagrams for ortho and para H2S follow straight lines given the uncertainties and yield T rot = 141 ± 12 K. This indicates H2S is in local thermodynamic equilibrium and is well characterized by a single kinetic temperature or an intense far-IR radiation field is redistributing the population to produce the observed trend. We argue the latter scenario is more probable and find that the most highly excited states (E up >~ 1000 K) are likely populated primarily by radiation pumping. We derive a column density, N tot(H2 32S) = 9.5 ± 1.9 × 1017 cm-2, gas kinetic temperature, T kin = 120+/- ^{13}_{10} K, and constrain the H2 volume density, n_H_2 >~ 9 × 10 7 cm-3, for the H2S emitting gas. These results point to an H2S origin in markedly dense, heavily embedded gas, possibly in close proximity to a hidden self-luminous source (or sources), which are conceivably responsible for Orion KL's high luminosity. We also derive an H2S ortho/para ratio of 1.7 ± 0.8 and set an upper limit for HDS/H2S of <4.9 × 10 -3. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  13. High selectivity ZIF-93 hollow fiber membranes for gas separation.

    PubMed

    Cacho-Bailo, Fernando; Caro, Guillermo; Etxeberría-Benavides, Miren; Karvan, Oğuz; Téllez, Carlos; Coronas, Joaquín

    2015-06-30

    Zeolitic imidazolate framework-93 (ZIF-93) continuous membranes were synthesized on the inner side of P84 co-polyimide hollow fiber supports by microfluidics. MOFs and polymers showed high compatibility and the membrane exhibited H2-CH4 and CO2-CH4 separation selectivities of 97 (100 °C) and 17 (35 °C), respectively.

  14. The effect of pore dimension of zeolites on the separation of gas mixtures

    NASA Astrophysics Data System (ADS)

    Jee, Sang Eun

    We examined the effect of the pore dimension of zeolites on the separation of gas mixtures using atomistic simulation methods. We studied two categories of the zeolites with small pores: pore modified silicalite for H2/CH4 separation and small pore silica zeolites for CO2/CH4 separation. The effect of pore modification of silicalite on the H2/CH4 separation was examined. Under some degrees of surface modification, the CH4 flux was reduced much more than the H2 flux, resulting in high ideal selectivities. The use of small pore zeolites for CO2/CH4 separations was studied. In DDR, we showed that CO2 diffusion rates are only weakly affected by the presence of CH4, even though the latter molecules diffuse very slowly. Consequently, therefore, the permeance of CO 2 in the equimolar mixtures is similar to the permeance for pure CO 2, while the CH4 permeance in the mixture is greatly reduced relatively to the pure component permeance. The calculated CO2/CH 4 separation selectivities are higher than 100 for a wide range of feed pressure, indicating excellent separation capabilities of DDR based membranes. Inspired by the observation in DDR we also examined the separation capabilities of 10 additional pure silica small pore zeolites for CO2/CH 4 separations. From these considerations, we predict that SAS, MTF and RWR will exhibit high separation selectivities because of their very high adsorption selectivities for CO2 over CH4. CHA and IHW, which have similar pore structures to DDR, showed comparable separation selectivities to DDR because of large differences in the diffusion rates of CO2 and CH4.

  15. Single-walled carbon nanotubes as stationary phase in gas chromatographic separation and determination of argon, carbon dioxide and hydrogen.

    PubMed

    Safavi, Afsaneh; Maleki, Norooz; Doroodmand, Mohammad Mahdi

    2010-08-24

    A chromatographic technique is introduced based on single-walled carbon nanotubes (SWCNTs) as stationary phase for separation of Ar, CO(2) and H(2) at parts per million (ppm) levels. The efficiency of SWCNTs was compared with solid materials such as molecular sieve, charcoal, multi-walled carbon nanotubes and carbon nanofibers. The morphology of SWCNTs was optimized for maximum adsorption of H(2), CO(2) and Ar and minimum adsorption of gases such as N(2), O(2), CO and H(2)O vapour. To control temperature of the gas chromatography column, peltier cooler was used. Mixtures of Ar, CO(2) and H(2) were separated according to column temperature program. Relative standard deviation for nine replicate analyses of 0.2 mL H(2) containing 10 microL of each Ar or CO(2) was 2.5% for Ar, 2.8% for CO(2) and 3.6% for H(2). The interfering effects of CO, and O(2) were investigated. Working ranges were evaluated as 40-600 ppm for Ar, 30-850 ppm for CO(2) and 10-1200 ppm for H(2). Significant sensitivity, small relative standard deviation (RSD) and acceptable limit of detection (LOD) were obtained for each analyte, showing capability of SWCNTs for gas separation and determination processes. Finally, the method was used to evaluate the contents of CO(2) in air sample.

  16. Giant enhancement of H2S gas response by decorating n-type SnO2 nanowires with p-type NiO nanoparticles

    NASA Astrophysics Data System (ADS)

    Van Hieu, Nguyen; Thi Hong Van, Phung; Tien Nhan, Le; Van Duy, Nguyen; Duc Hoa, Nguyen

    2012-12-01

    Metal oxide nanowires (NWs) are widely considered as promising materials for gas sensor applications. Here, we demonstrate that by decorating NiO nanoparticles on SnO2 NWs, the gas response to 10 ppm H2S increased up to ˜351-fold. The response of the NiO-decorated SnO2 NWs sensor to 10 ppm H2S at 300 °C reached ˜1372, whereas the cross-gas responses to 5 ppm NH3, 200 ppm C2H5OH, and 1 ppm NO2 were negligible (1.8 to 2.9). The enhanced H2S sensing performance was attributed by the catalytic effect of NiO and the formation of a continuous chain of n-p-n-p junctions.

  17. Chlorobium limicola forma thiosulfatophilum: Biocatalyst in the Production of Sulfur and Organic Carbon from a Gas Stream Containing H2S and CO2

    PubMed Central

    Cork, Douglas J.; Garunas, Ruta; Sajjad, Ashfaq

    1983-01-01

    Chlorobium limicola forma thiosulfatophilum (ATCC 17092) was grown in a 1-liter continuously stirred tank reactor (800-ml liquid volume) at pH 6.8, 30°C, saturated light intensity, and a gas flow rate of 23.6 ml/min from a gas cylinder blend consisting of 3.9 mol% H2S, 9.2 mol% CO2, 86.4 mol% N2, and 0.5 mol% H2. This is the first demonstration of photoautotrophic growth of a Chlorobium sp. on a continuous inorganic gas feed. A significant potential exists for applying this photoautotrophic process to desulfurization and CO2 fixation of gases containing acidic components (H2S and CO2). PMID:16346255

  18. Gas separation applications to METC-supported technologies

    SciTech Connect

    Poku, J.A.; Plunkett, J.E.

    1989-12-01

    The objectives of this study were to catalog both hot and cold gas separation technologies, to identify the status and the developers of each, and to identify how these separation processes might be applied to METC-supported technologies for removal of trace contaminants, or purification of gases used in or generated by coal processing. Discussions on gas separation process names, typical feeds, process developers, and operating conditions are provided in the following sections of this report, as well as descriptions of how these gas cleanup techniques would be used in developmental coal conversion technologies. 82 refs., 22 figs., 14 tabs.

  19. Investigation of Gas-Sensing Property of Acid-Deposited Polyaniline Thin-Film Sensors for Detecting H2S and SO2

    PubMed Central

    Dong, Xingchen; Zhang, Xiaoxing; Wu, Xiaoqing; Cui, Hao; Chen, Dachang

    2016-01-01

    Latent insulation defects introduced in manufacturing process of gas-insulated switchgears can lead to partial discharge during long-time operation, even to insulation fault if partial discharge develops further. Monitoring of decomposed components of SF6, insulating medium of gas-insulated switchgear, is a feasible method of early-warning to avoid the occurrence of sudden fault. Polyaniline thin-film with protonic acid deposited possesses wide application prospects in the gas-sensing field. Polyaniline thin-film sensors with only sulfosalicylic acid deposited and with both hydrochloric acid and sulfosalicylic acid deposited were prepared by chemical oxidative polymerization method. Gas-sensing experiment was carried out to test properties of new sensors when exposed to H2S and SO2, two decomposed products of SF6 under discharge. The gas-sensing properties of these two sensors were compared with that of a hydrochloric acid deposited sensor. Results show that the hydrochloric acid and sulfosalicylic acid deposited polyaniline thin-film sensor shows the most outstanding sensitivity and selectivity to H2S and SO2 when concentration of gases range from 10 to 100 μL/L, with sensitivity changing linearly with concentration of gases. The sensor also possesses excellent long-time and thermal stability. This research lays the foundation for preparing practical gas-sensing devices to detect H2S and SO2 in gas-insulated switchgears at room temperature. PMID:27834895

  20. Improving Hydrocarbon Separation In Gas Chromatography

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Woeller, F.; Kojiro, D. R.

    1983-01-01

    Modified solica spheres enhance chromatographic separation. Commercially available silica spheres are modified by reacting them with molecules containing isocyante and isothiocyanate groups. Applications of surface derivatized spheres that result from reaction include analysis of samples prouced by atmospheric or soil probes.

  1. Liquid absorbent solutions for separating nitrogen from natural gas

    DOEpatents

    Friesen, Dwayne T.; Babcock, Walter C.; Edlund, David J.; Lyon, David K.; Miller, Warren K.

    2000-01-01

    Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.

  2. Gas Phase Chiral Separations By Ion Mobility Spectrometry

    PubMed Central

    Dwivedi, Prabha; Wu, Ching; Hill, Herbert H.

    2013-01-01

    This manuscript introduces the concept of Chiral Ion Mobility Spectrometry (CIMS) and presents examples demonstrating the gas phase separation of enantiomers of a wide range of racemates including pharmaceuticals, amino acids and carbohydrates. CIMS is similar to traditional ion mobility spectrometry (IMS), where gas phase ions, when subjected to a potential gradient are separated at atmospheric pressure due to differences in their shapes and sizes. In addition to size and shape, CIMS separates ions based on their stereospecific interaction with a chiral gas. In order to achieve chiral discrimination by CIMS, an asymmetric environment was provided by doping the drift gas with a volatile chiral reagent. In this study S-(+)-2-butanol was used as a chiral modifier to demonstrate enantiomeric separations of atenolol, serine, methionine, threonine, methyl-α-glucopyranoside, glucose, penicillamine, valinol, phenylalanine, and tryptophan from their respective racemic mixtures. PMID:17165808

  3. Gas-Liquid Flows and Phase Separation

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    2004-01-01

    Common issues for space system designers include:Ability to Verify Performance in Normal Gravity prior to Deployment; System Stability; Phase Accumulation & Shedding; Phase Separation; Flow Distribution through Tees & Manifolds Boiling Crisis; Heat Transfer Coefficient; and Pressure Drop.The report concludes:Guidance similar to "A design that operates in a single phase is less complex than a design that has two-phase flow" is not always true considering the amount of effort spent on pressurizing, subcooling and phase separators to ensure single phase operation. While there is still much to learn about two-phase flow in reduced gravity, we have a good start. Focus now needs to be directed more towards system level problems .

  4. Synthesis of Highly Porous Coordination Polymers with Open Metal Sites for Enhanced Gas Uptake and Separation.

    PubMed

    Song, Kyung Seob; Kim, Daeok; Polychronopoulou, Kyriaki; Coskun, Ali

    2016-10-12

    Metal-containing amorphous microporous polymers are an emerging class of functional porous materials in which the surface properties and functions of polymers are dictated by the nature of the metal ions incorporated into the framework. In an effort to introduce coordinatively unsaturated metal sites into the porous polymers, we demonstrate herein an aqueous-phase synthesis of porous coordination polymers (PCPs) incorporating bis(o-diiminobenzosemiquinonato)-Cu(II) or -Ni(II) bridges by simply reacting hexaminotriptycene with CuSO4·5H2O [Cu(II)-PCP] or NiCl2·6H2O [Ni(II)-PCP] in H2O. The resulting polymers showed surface areas of up to 489 m(2) g(-1) along with a narrow pore size distribution. The presence of open metal sites significantly improved the gas affinity of these frameworks, leading to an exceptional isosteric heat of adsorption of 10.3 kJ·mol(-1) for H2 at zero coverage. The high affinities of Cu(II)- and Ni(II)-PCPs toward CO2 prompted us to investigate the removal of CO2 from natural and landfill gas conditions. We found that the higher affinity of Cu(II)-PCP compared to that of Ni(II)-PCP not only allowed for the tuning of the affinity of CO2 molecules toward the sorbent, but also led to an exceptional CO2/CH4 selectivity of 35.1 for landfill gas and 20.7 for natural gas at 298 K. These high selectivities were further verified by breakthrough measurements under the simulated natural and landfill gas conditions, in which both Cu(II)- and Ni(II)-PCPs showed complete removal of CO2. These results clearly demonstrate the promising attributes of metal-containing porous polymers for gas storage and separation applications.

  5. Calculating CO2 and H2O eddy covariance fluxes from an enclosed gas analyzer using an instantaneous mixing ratio 2159

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eddy covariance flux research has relied on open- or closed-path gas analyzers for producing estimates of net ecosystem exchange of carbon dioxide (CO2) and water vapor (H2O). The two instruments have had different challenges that have led to development of an enclosed design that is intended to max...

  6. Effect of the gas temperature and pressure on the nucleation time of particles in low pressure Ar-C2H2 rf plasmas

    NASA Astrophysics Data System (ADS)

    Lin, Jiashu; Henault, Marie; Orazbayev, Sagi; Boufendi, Laïa; Takahashi, Kazuo; Al Farabi Kazakh National University Collaboration; Kyoto Institute Of Technology Team; Gremi Team

    2016-09-01

    Particle formation in low pressure plasmas is a 3-step process. The first one corresponds to the nucleation and growth of nano-crystallites by ion-molecular reactions, the agglomeration phase to form large particles, and the growth by radical deposition on the particle surface. The nucleation phase was demonstrated to be sensitive to gas temperature and pressure. In this work, time of nucleation phase of particles formation in low pressure cold rf C2H2/Ar plasmas studied by varying gas temperature from 265 K to 375 K, gas pressure from 0.4 mbar to 0.8 mbar and rf power from 6 W to 20 W. The ratio of C2H2/Ar is fixed to 2/98 in terms of pressure. Several previous works reported that particle formation takes a few sec at room temperature in C2 H2 plasmas and the time is much shorter than 0.1 s in SiH4 plasmas. Time evolution of self-bias voltage was mainly used to determine nucleation time. The self-bias voltage was modified by phase transition between the steps from nucleation to coagulation. The experimental results showed that the nucleation time increased with gas temperature, decreased with gas pressure and discharge power. At constant gas pressure of 0.4 mbar and discharge power of 6 W, for example, the nucleation time increased from 5 sec to 30 sec with increas

  7. a Gas Phase Investigation of CuOH(H_2O)+ and Cu(II) Oligoglycine Water Oxidation Catalysts

    NASA Astrophysics Data System (ADS)

    Marsh, Brett; Zhou, Jia; Garand, Etienne

    2014-06-01

    The abundance of copper and copper compounds within the crust of the Earth and the well characterized coordination chemistry of copper species has led to investigation of copper as a catalyst for several different chemical reactions. Among the most notable of these has been the application of copper containing compounds to water oxidation. The chemistry used in this reaction has thus far been dominated by expensive materials containing the rare metals ruthenium or iridium. In this presentation we study several copper species which have attracted interest in this field including CuOH(H_2O)n+ clusters and Cu(II) oligoglycine complexes. We find that in the case of CuOH(H_2O)n+ clusters that the undercoordinated CuOH(H_2O)+ cluster has a strong affinity towards activating D2 while the higher coordinated CuOH(H_2O)2+ and CuOH(H_2O)3+ clusters show no propensity for the activation of D2. In the case of the Cu(II) oligoglycine complexes we find that the charge environment strongly affects the diagnostic CO stretch frequencies, creating a clear spectroscopic fingerprint for assessing the charge and interactions within these systems. Despite the small size (6-12 atoms) of the CuOH(H_2O)n+ clusters electronic structure methods including DFT and MP2 give poor agreement with the experimental results while DFT calculations on the relatively large Cu(II) oligoglycine species show excellent agreement with experiment.

  8. Process for separating aggressive gases from gas mixtures

    SciTech Connect

    Graham, T.E.

    1984-03-06

    A process for separating large percentages of aggressive gases such as carbon dioxide from low temperature gas mixtures wherein the gas mixture is passed through a plurality of treatment zones in series. In each treatment zone the gas mixture is first compressed to a pressure such that the partial pressure of the carbon dioxide is not greater than the critical carbon dioxide partial pressure and the compressed gas mixture is then brought into contact with a membrane more permeable to carbon dioxide than other gases of the mixture such that carbon dioxide permeates the membrane to the other side thereof. The gas mixture is maintained in contact with the membrane a sufficient time to lower the partial pressure of the carbon dioxide in the non-permeated gas mixture to less than about 40 percent of said critical carbon dioxide partial pressure. The process is especially useful for separating carbon dioxide from methane and other gases.

  9. Functionalized inorganic membranes for gas separation

    DOEpatents

    Ku, Anthony Yu-Chung; Ruud, James Anthony; Molaison, Jennifer Lynn; Schick, Louis Andrew ,; Ramaswamy, Vidya

    2008-07-08

    A porous membrane for separation of carbon dioxide from a fluid stream at a temperature higher than about 200.degree. C. with selectivity higher than Knudsen diffusion selectivity. The porous membrane comprises a porous support layer comprising alumina, silica, zirconia or stabilized zirconia; a porous separation layer comprising alumina, silica, zirconia or stabilized zirconia, and a functional layer comprising a ceramic oxide contactable with the fluid stream to preferentially transport carbon dioxide. In particular, the functional layer may be MgO, CaO, SrO, BaO, La.sub.2O.sub.3, CeO.sub.2, ATiO.sub.3, AZrO.sub.3, AAl.sub.2O.sub.4, A.sup.1FeO.sub.3, A.sup.1MnO.sub.3, A.sup.1CoO.sub.3, A.sup.1NiO.sub.3, A.sup.2HfO.sub.3, A.sup.3CeO.sub.3, Li.sub.2ZrO.sub.3, Li.sub.2SiO.sub.3, Li.sub.2TiO.sub.3 or a mixture thereof; wherein A is Mg, Ca, Sr or Ba; A.sup.1 is La, Ca, Sr or Ba; A.sup.2 is Ca, Sr or Ba; and A.sup.3 is Sr or Ba.

  10. The RealGas and RealGasH2O options of the TOUGH+ code for the simulation of coupled fluid and heat flow in tight/shale gas systems

    NASA Astrophysics Data System (ADS)

    Moridis, George J.; Freeman, Craig M.

    2014-04-01

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas. The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and shale gas) reservoirs. The gas mixture is treated as either a single-pseudo-component having a fixed composition, or as a multicomponent system composed of up to 9 individual real gases. The RealGas option has the same general capabilities, but does not include water, thus describing a single-phase, dry-gas system. In addition to the standard capabilities of all members of the TOUGH+ family of codes (fully-implicit, compositional simulators using both structured and unstructured grids), the capabilities of the two codes include coupled flow and thermal effects in porous and/or fractured media, real gas behavior, inertial (Klinkenberg) effects, full micro-flow treatment, Darcy and non-Darcy flow through the matrix and fractures of fractured media, single- and multi-component gas sorption onto the grains of the porous media following several isotherm options, discrete and fracture representation, complex matrix-fracture relationships, and porosity-permeability dependence on pressure changes. The two options allow the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in problems of geologic storage of greenhouse gas mixtures, and of geothermal reservoirs with multi-component condensable (H2O and CH4) and non-condensable gas mixtures. The codes are verified against available analytical and semi-analytical solutions. Their capabilities are demonstrated in a series of problems of increasing complexity, ranging from isothermal flow in simpler 1D and 2D conventional gas reservoirs, to non-isothermal gas flow in 3D fractured shale gas reservoirs involving 4 types of fractures, micro-flow, non-Darcy flow and gas

  11. The RealGas and RealGasH2O Options of the TOUGH+ Code for the Simulation of Coupled Fluid and Heat Flow in Tight/Shale Gas Systems

    SciTech Connect

    Moridis, George; Freeman, Craig

    2013-09-30

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas . The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and shale gas) reservoirs. The gas mixture is treated as either a single-pseudo-component having a fixed composition, or as a multicomponent system composed of up to 9 individual real gases. The RealGas option has the same general capabilities, but does not include water, thus describing a single-phase, dry-gas system. In addition to the standard capabilities of all members of the TOUGH+ family of codes (fully-implicit, compositional simulators using both structured and unstructured grids), the capabilities of the two codes include: coupled flow and thermal effects in porous and/or fractured media, real gas behavior, inertial (Klinkenberg) effects, full micro-flow treatment, Darcy and non-Darcy flow through the matrix and fractures of fractured media, single- and multi-component gas sorption onto the grains of the porous media following several isotherm options, discrete and fracture representation, complex matrix-fracture relationships, and porosity-permeability dependence on pressure changes. The two options allow the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in problems of geologic storage of greenhouse gas mixtures, and of geothermal reservoirs with multi-component condensable (H2O and CH4) and non-condensable gas mixtures. The codes are verified against available analytical and semi-analytical solutions. Their capabilities are demonstrated in a series of problems of increasing complexity, ranging from isothermal flow in simpler 1D and 2D conventional gas reservoirs, to non-isothermal gas flow in 3D fractured shale gas reservoirs involving 4 types of fractures, micro-flow, non-Darcy flow and gas

  12. Why do the HIghMass Galaxies Have so Much Gas?: Studying Massive, Gas-Rich Galaxies at z~0 with Resolved HI and H2

    NASA Astrophysics Data System (ADS)

    Hallenbeck, Gregory L.; HIghMass Team

    2016-01-01

    In the standard ΛCDM cosmology, galaxies form via mergers of many smaller dark matter halos. Because mergers drive star formation, the most massive galaxies should also be the ones which have been the most efficient at converting their gas reservoirs into stars. This trend is seen observationally: in general, as stellar mass increases, gas fraction (GF = MHI/M*) decreases. Galaxies which have large reservoirs of atomic hydrogen (HI) are thus expected to be extremely rare, which was seemingly supported by earlier blind HI surveys.In seeming contradiction, ALFALFA, the Arecibo Legacy Fast ALFA Survey has observed a sample of 34 galaxies which are both massive (MHI>1010 M⊙) and have unusually high gas fractions (all ≥ 0.3; half are > 1). We call this sample HighMass. Unlike other extremely HI-massive samples, such galaxies are neither low surface brightness galaxies nor are they simply "scaled up" spirals. Could this gas be recently acquired, either from accreting small companions or directly from the cosmic web? Or is it primordial, and has been kept from forming stars, possibly because of an unusually high dark matter halo spin parameter?We present resolved HI, H2, and star formation properties of three of these HIghMass galaxies, and compare them with two HIghMass galaxies previously discussed in Hallenbeck et al. (2014). One of these galaxies, UGC 6168, appears in the process of transitioning from a quiescent to star-forming phase, as indicated by its bar and potential non-circular flows. A second, UGC 7899, has a clear warp, which could be evidence of recently accreted gas—but the presence of a warp is far from conclusive evidence. Both have moderately high dark matter halo spin parameters (λ' = 0.09), similar to the previously studied UGC 9037. The third, NGC 5230, looks undisturbed both optically and in its radio emission, but is in a group full of extragalactic gas. A neighboring galaxy has been significantly disrupted, and NGC 5230 may be in the

  13. Fast gas chromatographic separation of biodiesel.

    SciTech Connect

    Pauls, R. E.

    2011-05-01

    A high-speed gas chromatographic method has been developed to determine the FAME distribution of B100 biodiesel. The capillary column used in this work has dimensions of 20 m x 0.100 mm and is coated with a polyethylene glycol film. Analysis times are typically on the order of 4-5 min depending upon the composition of the B100. The application of this method to a variety of vegetable and animal derived B100 is demonstrated. Quantitative results obtained with this method were in close agreement with those obtained by a more conventional approach on a 100 m column. The method, coupled with solid-phase extraction, was also found suitable to determine the B100 content of biodiesel-diesel blends.

  14. Sensitive, Selective, and Fast Detection of ppb-Level H2S Gas Boosted by ZnO-CuO Mesocrystal

    NASA Astrophysics Data System (ADS)

    Guo, Yanan; Gong, Miaomiao; Li, Yushu; Liu, Yunling; Dou, Xincun

    2016-10-01

    ZnO-CuO mesocrystal was prepared via topotactic transformation using one-step direct annealing of aqueous precursor solution and assembled into a H2S sensor. The ZnO-CuO mesocrystal-based sensor possesses good linearity and high sensitivity in the low-concentration range (10-200 ppb). Compared to pure CuO, the as-prepared ZnO-CuO mesocrystal sensor exhibited superior H2S sensing performance with a response ranging from 8.6 to 152 % towards H2S concentrations from 10 ppb to 10 ppm when applied at the optimized working temperature of 125 °C. The sensor showed excellent repeatability and good selectivity towards H2S gas even at a concentration four orders of magnitude lower than the interfering gases, such as H2, CO2, CO, NO2, acetone, and NH3. The improved sensitivity could be attributed partially to the effective diffusion of analyte gas through the mesocrystal surface and the abundant accessible active sites. Moreover, the nanoscale p-n junctions within the mesocrystal, which could effectively manipulate the local charge carrier concentration, are also beneficial to boost the sensing performance.

  15. Evaluation of Mars CO2 Capture and Gas Separation Technologies

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony C.; Santiago-Maldonado, Edgardo; Gibson, Tracy; Devor, Robert; Captain, James

    2011-01-01

    Recent national policy statements have established that the ultimate destination of NASA's human exploration program is Mars. In Situ Resource Utilization (ISRU) is a key technology required to ,enable such missions and it is appropriate to review progress in this area and continue to advance the systems required to produce rocket propellant, oxygen, and other consumables on Mars using the carbon dioxide atmosphere and other potential resources. The Mars Atmospheric Capture and Gas separation project is selecting, developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Trace gases will be required to be separated from Martian atmospheric gases to provide pure CO2 to processing elements. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and should be captured as well. To achieve these goals, highly efficient gas separation processes will be required. These gas separation techniques are also required across various areas within the ISRU project to support various consumable production processes. The development of innovative gas separation techniques will evaluate the current state-of-the-art for the gas separation required, with the objective to demonstrate and develop light-weight, low-power methods for gas separation. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from unreacted carbon oxides (C02-CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, (3)/carbon oxides from oxygen from a trash/waste processing reaction, and (4) helium from hydrogen or oxygen from a propellant scavenging process. Potential technologies for the separations include' freezers, selective membranes, selective solvents, polymeric sorbents

  16. Thermophoretic separation of aerosol particles from a sampled gas stream

    DOEpatents

    Postma, Arlin K.

    1986-01-01

    A method for separating gaseous samples from a contained atmosphere that includes aerosol particles uses the step of repelling particles from a gas permeable surface or membrane by heating the surface to a temperature greater than that of the surrounding atmosphere. The resulting thermophoretic forces maintain the gas permeable surface clear of aerosol particles. The disclosed apparatus utilizes a downwardly facing heated plate of gas permeable material to combine thermophoretic repulsion and gravity forces to prevent particles of any size from contacting the separating plate surfaces.

  17. Molecular dynamics investigation of separation of hydrogen sulfide from acidic gas mixtures inside metal-doped graphite micropores.

    PubMed

    Huang, Pei-Hsing

    2015-09-21

    The separation of poisonous compounds from various process fluids has long been highly intractable, motivating the present study on the dynamic separation of H2S in acidic-gas-mixture-filled micropores. The molecular dynamics approach, coupled with the isothermal-isochoric ensemble, was used to model the molecular interactions and adsorption of H2S/CO2/CO/H2O mixtures inside metal-doped graphite slits. Due to the difference in the adsorption characteristics between the two distinct adsorbent materials, the metal dopant in the graphitic micropores leads to competitive adsorption, i.e. the Au and graphite walls compete to capture free adsorbates. The effects of competitive adsorption, coupled with changes in the gas temperature, concentration, constituent ratio and slit width on the constituent separation of mixtures were systematically studied. The molecule-wall binding energies calculated in this work (those of H2S, H2O and CO on Au walls and those of H2O, CO and CO2 on graphite walls) show good agreement with those obtained using density functional theory (DFT) and experimental results. The z-directional self-diffusivities (Dz) for adsorbates inside the slit ranged from 10(-9) to 10(-7) m(2) s(-1) as the temperature was increased from 10 to 500 K. The values are comparable with those for a typical microporous fluid (10(-8)-10(-9) m(2) s(-1) in a condensed phase and 10(-6)-10(-7) m(2) s(-1) in the gaseous state). The formation of H-bonding networks and hydrates of H2S is disadvantageous for the separation of mixtures. The results indicate that H2S can be efficiently separated from acidic gas mixtures onto the Au(111) surface by (i) reducing the mole fraction of H2S and H2O in the mixtures, (ii) raising the gas temperature to the high temperature limit (≥400 K), and (iii) lowering the slit width to below the threshold dimension (≤23.26 Å).

  18. An Experimental Study of Atmospheric Homogeneous Nucleation: Cluster Growth and Gas-Particle Reactions of H2SO4

    NASA Technical Reports Server (NTRS)

    Eisele, F. L.

    1996-01-01

    The work proposed on this project included both field and laboratory studies. The laboratory studies were to consist of measurements of H2SO4 uptake and evaporation from aerosols of varying chemical composition, while the field component would include measurements of H2SO4 and other compounds which would be conducted as part of a large field campaign. By chance, the opportunity to conduct such an H2SO4/aerosol/ultrafine particle study in conjunction with an OH intercomparison/photochemistry study became available very early in this project (September 1993). This study was conducted at Caribou, Colorado in conjunction with several other groups from NCAR, NOAA and a number of universities. Our group measured OH, H2SO4, SO2, and H20, while Dr. McMurfy's group measured ultrafine particles, and total particle number and size distribution. In addition measurements of HO2/RO2, O3, NO, NO2, NO(y) CO, hydrocarbons, CH2O, and other chemical compounds and meteorological parameters were performed by the other participants and a new laser oblation/mass spectrometry technique was also employed by the NOAA Aeronomy Laboratory to study aerosol composition. The study of aerosol production and growth in conjunction with photochemical measurements is highly advantageous because particle growth precursors such as H2SO4.or MSA are formed by OH initiated sulfur oxidation. The large number of hydrocarbon measurements included in this study were also important in understanding particle growth.

  19. Effects of different petal thickness on gas sensing properties of flower-like WO3·H2O hierarchical architectures

    NASA Astrophysics Data System (ADS)

    Zeng, Wen; Zhang, He; Wang, Zhongchang

    2015-08-01

    Hierarchical architectures consisting of two-dimensional (2D) nanostructures are of great interest for potential use in recent year. Here, we report the successful synthesis of four hierarchical tungsten oxide flower-like architectures via a simple yet facile hydrothermal method. The as-prepared WO3·H2O hierarchical architectures are in fact assembled with numerous nanosheets or nanoplates. Through a comprehensive characterization of microstructures and morphologies of the as-prepared products, we find that petal thickness is a key factor for affecting gas-sensing performances. We further propose a possible growth mechanism for the four flower-like architectures. Moreover, gas-sensing measurements showed that the well-defined sheet-flower WO3·H2O hierarchical architectures exhibited the excellent gas-sensing properties to ethanol owing to their largest amount of thin petal structures and pores.

  20. Evaluation and Characterization of Membranes for HI/H2O/I2 Water Separation for the S-I Cycle

    SciTech Connect

    Frederick F. Stewart

    2005-09-01

    In the Sulfur-Iodine (S-I) thermochemical cycle, iodine is added to the product of the Bunsen reaction to facilitate the separation of sulfuric acid (H2SO4) from hydriodic acid (HI). The amount of iodine can be as high as 83% of the overall mass load of the Bunsen product stream, which potentially introduces a large burden on the cycle’s efficiency. Removal of water from the HI and I2 mixture would substantially reduce the amount of required additional iodine. In this work, Nafion® membranes have been studied for their use as de-watering membranes. Specifically, two thicknesses of Nafion membranes have been found to be effective in this application. The thicker membrane, Nafion-117®, produces moderate fluxes of water with very high separation factors. On the other hand, the thinner membrane, Nafion-112®, yielded very large fluxes of water, however with smaller separation factors. All membranes were found to be durable and did not degrade in contact with the feed stream over periods of time up to three months.

  1. First experimental determination of the absolute gas-phase rate coefficient for the reaction of OH with 4-hydroxy-2-butanone (4H2B) at 294 K by vapor pressure measurements of 4H2B.

    PubMed

    El Dib, Gisèle; Sleiman, Chantal; Canosa, André; Travers, Daniel; Courbe, Jonathan; Sawaya, Terufat; Mokbel, Ilham; Chakir, Abdelkhaleq

    2013-01-10

    The reaction of the OH radicals with 4-hydroxy-2-butanone was investigated in the gas phase using an absolute rate method at room temperature and over the pressure range 10-330 Torr in He and air as diluent gases. The rate coefficients were measured using pulsed laser photolysis (PLP) of H(2)O(2) to produce OH and laser induced fluorescence (LIF) to measure the OH temporal profile. An average value of (4.8 ± 1.2) × 10(-12) cm(3) molecule(-1) s(-1) was obtained. The OH quantum yield following the 266 nm pulsed laser photolysis of 4-hydroxy-2-butanone was measured for the first time and found to be about 0.3%. The investigated kinetic study required accurate measurements of the vapor pressure of 4-hydroxy-2-butanone, which was measured using a static apparatus. The vapor pressure was found to range from 0.056 to 7.11 Torr between 254 and 323 K. This work provides the first absolute rate coefficients for the reaction of 4-hydroxy-2-butanone with OH and the first experimental saturated vapor pressures of the studied compound below 311 K. The obtained results are compared to those of the literature and the effects of the experimental conditions on the reactivity are examined. The calculated tropospheric lifetime obtained in this work suggests that once emitted into the atmosphere, 4H2B may contribute to the photochemical pollution in a local or regional scale.

  2. Gas-phase thermometry using delayed-probe-pulse picosecond coherent anti-Stokes Raman scattering spectra of H2.

    PubMed

    Stauffer, Hans U; Kulatilaka, Waruna D; Hsu, Paul S; Gord, James R; Roy, Sukesh

    2011-02-01

    We report the development and application of a simple theoretical model for extracting temperatures from picosecond-laser-based coherent anti-Stokes Raman scattering (CARS) spectra of H2 obtained using time-delayed probe pulses. This approach addresses the challenges associated with the effects of rotational-level-dependent decay lifetimes on time-delayed probing for CARS thermometry. A simple procedure is presented for accurate temperature determination based on a Boltzmann distribution using delayed-probe-pulse vibrational CARS spectra of H2; this procedure requires measurement at only a select handful of probe-pulse delays and requires no assumptions about sample environment.

  3. Bifunctional Sensing Mechanism of SnO2-ZnO Composite Nanofibers for Drastically Enhancing the Sensing Behavior in H2 Gas.

    PubMed

    Katoch, Akash; Kim, Jae-Hun; Kwon, Yong Jung; Kim, Hyoun Woo; Kim, Sang Sub

    2015-06-03

    SnO2-ZnO composite nanofibers fabricated using an electrospinning method exhibited exceptional hydrogen (H2) sensing behavior. The existence of tetragonal SnO2 and hexagonal ZnO nanograins was confirmed by an analysis of the crystalline phase of the composite nanofibers. A bifunctional sensing mechanism of the composite nanofibers was proposed in which the combined effects of SnO2-SnO2 homointerfaces and ZnO-SnO2 heterointerfaces contributed to an improvement in the H2 sensing characteristics. The sensing process with respect to SnO2-ZnO heterojunctions is associated not only with the high barrier at the junctions, but also the semiconductor-to-metallic transition on the surface of the ZnO nanograins upon the introduction of H2 gas.

  4. Action mechanism of hydrogen gas on deposition of HfC coating using HfCl4-CH4-H2-Ar system

    NASA Astrophysics Data System (ADS)

    Wang, Yalei; Li, Zehao; Xiong, Xiang; Li, Xiaobin; Chen, Zhaoke; Sun, Wei

    2016-12-01

    Hafnium carbide coatings were deposited on carbon/carbon composites by low pressure chemical vapor deposition using HfCl4-CH4-H2-Ar system. The microstructure, mechanical and ablation resistance performance of HfC coatings deposited with various H2 concentrations were investigated. The effect of hydrogen gas on the deposition of HfC coating was also discussed. Results show that all of the deposited coatings are composed of single cubic HfC phase, the hydrogen gas acted as a crucial role in determining the preferred orientation, microstructure and growth behavior of HfC coatings. During the deposition process, the gas phase supersaturation of the reaction species can be controlled by adjusting the hydrogen gas concentration. When deposited with low hydrogen gas concentration, the coating growth was dominated by the nucleation of HfC, which results in the particle-stacked structure of HfC coating. Otherwise, the coating growth was dominated by the crystal growth at high hydrogen gas concentration, which leads to the column-arranged structure of HfC coating. Under the ablation environment, the coating C2 exhibits better configurational stability and ablation resistance. The coating structure has a significant influence on the mechanical and ablation resistance properties of HfC coating.

  5. Advanced Sorbents as a Versatile Platform for Gas Separation

    SciTech Connect

    Neil Stephenson

    2003-09-30

    The program objective was to develop materials and processes for industrial gas separations to reduce energy use and enable waste reduction. The approach chosen combined novel oxygen selective adsorbents and pressure swing adsorption (PSA) processes. Preliminary materials development and process simulation results indicated that oxygen selective adsorbents could provide a versatile platform for industrial gas separations. If fully successful, this new technology offered the potential for reducing the cost of producing nitrogen/oxygen co-products, high purity nitrogen, argon, and possibly oxygen. The potential energy savings for the gas separations are appreciable, but the end users are the main beneficiaries. Lowering the cost of industrial gases expands their use in applications that can employ them for reducing energy consumption and emissions.

  6. Spectroscopic and modeling investigations of the gas-phase chemistry and composition in microwave plasma activated B2H6/Ar/H2 mixtures.

    PubMed

    Ma, Jie; Richley, James C; Davies, David R W; Cheesman, Andrew; Ashfold, Michael N R; Mankelevich, Yuri A

    2010-02-25

    This paper describes a three-pronged study of microwave (MW) activated B(2)H(6)/Ar/H(2) plasmas as a precursor to diagnosis of the B(2)H(6)/CH(4)/Ar/H(2) plasmas used for the chemical vapor deposition of B-doped diamond. Absolute column densities of B atoms and BH radicals have been determined by cavity ring-down spectroscopy as a function of height (z) above a molybdenum substrate and of the plasma process conditions (B(2)H(6) and Ar partial pressures, total pressure, and supplied MW power). Optical emission spectroscopy has been used to explore variations in the relative densities of electronically excited BH, H, and H(2) species as a function of the same process conditions and of time after introducing B(2)H(6) into a pre-existing Ar/H(2) plasma. The experimental measurements are complemented by extensive 2-D(r, z) modeling of the plasma chemistry, which results in refinements to the existing B/H chemistry and thermochemistry and demonstrates the potentially substantial loss of gas-phase BH(x) species through reaction with trace quantities of air/O(2) in the process gas mixture and heterogeneous processes occurring at the reactor wall.

  7. Comparative investigation on chemical looping combustion of coal-derived synthesis gas containing H2S over supported NiO oxygen carriers

    SciTech Connect

    Ksepko, E.; Siriwardane, R.; Tian, H.; Simonyi, T.; Sciazko, M.

    2010-01-01

    Chemical looping combustion (CLC) of simulated coal-derived synthesis gas was conducted with NiO oxygen carriers supported on SiO2, ZrO2, TiO2, and sepiolite. The effect of H2S on the performance of these samples for the CLC process was also evaluated. Five-cycle thermogravimetric analysis (TGA) tests at 800 C indicated that all oxygen carriers had a stable performance at 800 C, except NiO/SiO2. Full reduction/oxidation reactions of the oxygen carrier were obtained during the five-cycle test. It was found that support had a significant effect on reaction performance of NiO both in reduction and oxidation rates. The reduction reaction was significantly faster than the oxidation reaction for all oxygen carriers, while the oxidation reaction is fairly slow due to oxygen diffusion on NiO layers. The reaction profile was greatly affected by the presence of H2S, but there was no effect on the capacity due to the presence of H2S in synthesis gas. The presence of H2S decreased reduction reaction rates significantly, but oxidation rates of reduced samples increased. X-ray diffraction (XRD) data of the oxidized samples after a five-cycle test showed stable crystalline phases without any formation of sulfides or sulfites/sulfates. Increase in reaction temperature to 900 C had a positive effect on the performance.

  8. Non-Controlled Emission of Inorganic Toxic gas Components (CO, H2S, NH3 and Hg0) to the atmosphere from Arico's landfill, Tenerife, Canary Islands, Spain

    NASA Astrophysics Data System (ADS)

    Echeita, A.; Perez, C.; Hernandez, C.; Fariña, L.; Lima, R.; Salazar, J.; Hernandez, P.; Perez, N.

    2001-12-01

    Landfill gas is mainly constituted by CO2 and CH4. However, other inorganic toxic gas components such as CO, NH3, H2S and Hg0, are also present. Reduced gas species are produced and released during the anaerobic decomposition of urban waste, while Hg0 is originally present in the waste and it is released as a volatile. Significant amounts of non-controlled emission of these components could be released to the atmosphere in the form of diffuse degassing, The goal of this study is to evaluate the "non-controlled" emissions of these inorganic toxic gas components from Arico's landfill, Tenerife. Arico's landfill (0.35 Km2) holds about 1,200 t/d of urban solid waste with an average organic matter content of 48%. Diffuse CO2 emission has been measured at the surface of Arico's landfill by means of a NDIR according with the accumulation chamber method. Landfill gases were also collected at 40 cm depth using a metallic probe and analyzed within 24 hours for CO2 and CO composition by means of a VARIAN micro-GC QUAD. H2S and Hg0 were analyzed by means of a Polytron-II electrochemical sensor and a JEROME 431-X mercury analyzer, respectively. NH3 was fixed in a boric acid solution and determined by means of a selective electrode. CO concentration ranged from non-detectable to 2,531 ppmv, with a median of 24.3 ppmv. The highest observed Hg0 concentration in the surface landfill gas is 0.004 ppbv, while H2S concentration reached levels up to 12 ppmv. NH3 contents were lower than 1 ppmv. CO, Hg0, H2S and NH3 fluxes have been estimated by multiplying CO2 efflux times (Tox.I.C.)i/CO2 where (Tox.I.C.)i is the concentration of CO, Hg0, H2S and NH3. The highest efflux values for CO, Hg0, H2S and NH3 were 6.8 gm-2d-1, 0.04 µ gm-2d-1, 1.7 mgm-2d-1 and 0.23 gm-2d-1, respectively.

  9. H2SO4 formation from the gas-phase reaction of stabilized Criegee Intermediates with SO2: Influence of water vapour content and temperature

    NASA Astrophysics Data System (ADS)

    Berndt, Torsten; Jokinen, Tuija; Sipilä, Mikko; Mauldin, Roy L.; Herrmann, Hartmut; Stratmann, Frank; Junninen, Heikki; Kulmala, Markku

    2014-06-01

    The importance of gas-phase products from alkene ozonolysis other than OH radicals, most likely stabilized Criegee Intermediates (sCI), for the process of atmospheric SO2 oxidation to H2SO4 has been recently discovered. Subjects of this work are investigations on H2SO4 formation as a function of water vapour content (RH = 2-65%) and temperature (278-343 K) starting from the ozonolysis of trans-2-butene and 2,3-dimethyl-2-butene (TME). H2SO4 production other than via the OH radical reaction was attributed to the reaction of SO2 with sCI, i.e. acetaldehyde oxide arising from trans-2-butene ozonolysis and acetone oxide from TME. Measurements have been conducted in an atmospheric pressure flow tube using NO3--CI-APi-TOF mass spectrometry for H2SO4 detection. The sCI yields derived from H2SO4 measurements at 293 K were 0.49 ± 0.22 for acetaldehyde oxide and 0.45 ± 0.20 for acetone oxide. Our findings indicate a H2SO4 yield from sCI + SO2 of unity or close to unity. The deduced rate coefficient ratio for the reaction of sCI with H2O and SO2, k(sCI + H2O)/k(sCI + SO2), was found to be strongly dependent on the structure of the Criegee Intermediate, for acetaldehyde oxide at 293 K: (8.8 ± 0.4)·10-5 (syn- and anti-conformer in total) and for acetone oxide: <4·10-6. H2SO4 formation from sCI was pushed back with rising temperature in both reaction systems most probably due to an enhancement of sCI decomposition. The ratio k(dec)/k(sCI + SO2) increased by a factor of 34 (acetone oxide) increasing the temperature from 278 to 343 K. In the case of acetaldehyde oxide the temperature effect is less pronounced. The relevance of atmospheric H2SO4 formation via sCI + SO2 is discussed in view of its dependence on the structure of the Criegee Intermediate.

  10. H2 Detection via Polarography

    NASA Technical Reports Server (NTRS)

    Dominquez, Jesus; Barile, Ron

    2006-01-01

    Polarography is the measurement of the current that flows in solution as a function of an applied voltage. The actual form of the observed polarographic current depends upon the manner in which the voltage is applied and on the characteristics of the working electrode. The new gas polarographic H2 sensor shows a current level increment with concentration of the gaseous H2 similar to those relating to metal ions in liquid electrolytes in well-known polarography. This phenomenon is caused by the fact that the diffusion of the gaseous H2 through a gas diffusion hole built in the sensor is a rate-determining step in the gaseous-hydrogen sensing mechanism. The diffusion hole artificially limits the diffusion of the gaseous H2 toward the electrode located at the sensor cavity. This gas polarographic H2 sensor is actually an electrochemical-pumping cell since the gaseous H2 is in fact pumped via the electrochemical driving force generated between the electrodes. Gaseous H2 enters the diffusion hole and reaches the first electrode (anode) located in the sensor cavity to be transformed into an H ions or protons; H ions pass through the electrolyte and reach the second electrode (cathode) to be reformed to gaseous H2. Gas polarographic O2 sensors are commercially available; a gas polarographic O2 sensor was used to prove the feasibility of building a new gas polarographic H2 sensor.

  11. An efficient polymer molecular sieve for membrane gas separations.

    PubMed

    Carta, Mariolino; Malpass-Evans, Richard; Croad, Matthew; Rogan, Yulia; Jansen, Johannes C; Bernardo, Paola; Bazzarelli, Fabio; McKeown, Neil B

    2013-01-18

    Microporous polymers of extreme rigidity are required for gas-separation membranes that combine high permeability with selectivity. We report a shape-persistent ladder polymer consisting of benzene rings fused together by inflexible bridged bicyclic units. The polymer's contorted shape ensures both microporosity-with an internal surface area greater than 1000 square meters per gram-and solubility so that it is readily cast from solution into robust films. These films demonstrate exceptional performance as molecular sieves with high gas permeabilities and good selectivities for smaller gas molecules, such as hydrogen and oxygen, over larger molecules, such as nitrogen and methane. Hence, this polymer has excellent potential for making membranes suitable for large-scale gas separations of commercial and environmental relevance.

  12. Efficient methods for screening of metal organic framework membranes for gas separations using atomically detailed models.

    PubMed

    Keskin, Seda; Sholl, David S

    2009-10-06

    Metal organic frameworks (MOFs) define a diverse class of nanoporous materials having potential applications in adsorption-based and membrane-based gas separations. We have previously used atomically detailed models to predict the performance of MOFs for membrane-based separations of gases, but these calculations require considerable computational resources and time. Here, we introduce an efficient approximate method for screening MOFs based on atomistic models that will accelerate the modeling of membrane applications. The validity of this approximate method is examined by comparison with detailed calculations for CH4/H2, CO2/CH4, and CO2/H2 mixtures at room temperature permeating through IRMOF-1 and CuBTC membranes. These results allow us to hypothesize a connection between two computationally efficient correlations predicting mixture adsorption and mixture self-diffusion properties and the validity of our approximate screening method. We then apply our model to six additional MOFs, IRMOF-8, -9, -10, and -14, Zn(bdc)(ted)0.5, and COF-102, to examine the effect of chemical diversity and interpenetration on the performance of metal organic framework membranes for light gas separations.

  13. Determining noble gas partitioning within a CO2-H2O system at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Warr, Oliver; Rochelle, Christopher A.; Masters, Andrew; Ballentine, Christopher J.

    2015-06-01

    Quantifying the distribution of noble gases between phases is essential for using these inert trace gases to track the processes controlling multi-phase subsurface systems. Here we present experimental data that defines noble gas partitioning for two phase CO2-water systems. These are at the pressure and temperature range relevant for engineered systems used for anthropogenic carbon capture and geological storage (CCS) technologies, and CO2-rich natural gas reservoirs (CO2 density range 169-656 kg/m3 at 323-377 K and 89-134 bar). The new partitioning data are compared to predictions of noble gas partitioning determined in low-pressure, pure noble gas-water systems for all noble gases except neon and radon. At low CO2 density there was no difference between measured noble gas partitioning and that predicted in pure noble gas-water systems. At high CO2 density, however, partition coefficients express significant deviation from pure noble gas-water systems. At 656 kg/m3, these deviations are -35%, 74%, 113% and 319% for helium, argon, krypton and xenon, respectively. A second order polynomial fit to the data for each noble gas describes the deviation from the pure noble gas-water system as a function of CO2 density. We argue that the difference between pure noble gas-water systems and the high density CO2-water system is due to an enhanced degree of molecular interactions occurring within the dense CO2 phase due to the combined effect of inductive and dispersive forces acting on the noble gases. As the magnitude of these forces are related to the size and polarisability of each noble gas, xenon followed by krypton and argon become significantly more soluble within dense CO2. In the case of helium repulsive forces dominate and so it becomes less soluble as a function of CO2 density.

  14. Ceramic membranes for gas separation at high temperatures. Final report

    SciTech Connect

    Wang, C.J.

    1994-03-01

    Superior heat, wear, erosion, and corrosion resistance of ceramic materials have motivated the studies of processing-structure-performance interrelationships of ceramic membranes for high temperature gas separations. A literature review on pore transport mechanisms, physical structure of membranes, and module configuration of industrial membrane processes has been made to obtain a better understanding of membrane performance in gas separations. The research experience in decomposing polymer resins for ablative composites has stimulated a research interest in developing a dynamic model for membrane processes, incorporating a temperature effects on material and fluid properties. Brief summaries of the reviewed literature, permeability experiments, and process modeling are presented in this report.

  15. Porous liquids: A promising class of media for gas separation

    SciTech Connect

    Zhang, Jinshui; Chai, Song -Hai; Qiao, Zhen -An; Mahurin, Shannon M.; Chen, Jihua; Fang, Youxing; Wan, Shun; Nelson, Kimberly; Zhang, Pengfei; Dai, Sheng

    2014-11-17

    In porous liquids with empty cavities we successfully has been successfully fabricated by surface engineering of hollow structures with suitable corona and canopy species. By taking advantage of the liquid-like polymeric matrices as a separation medium and the empty cavities as gas transport pathway, this unique porous liquid can function as a promising candidate for gas separation. A facile synthetic strategy can be further extended to other types of nanostructure-based porous liquid fabrication, opening up new opportunities for preparation of porous liquids with attractive properties for specific tasks.

  16. Microporous organic polymers for gas storage and separation applications.

    PubMed

    Chang, Ze; Zhang, Da-Shuai; Chen, Qiang; Bu, Xian-He

    2013-04-21

    Microporous organic polymers (MOPs), an emerging class of functional porous materials featured with the pure organic component have been widely studied in recent years. These materials have potential uses in areas such as storage, separation, and catalysis. In this Perspective, we focused on the gas storage and separation of MOPs. The targeted design and synthesis of MOPs toward the enhancement of gas capacity and selectivity are discussed. Furthermore, special emphasis is given to the post-synthesis modification of MOPs which have been proved to be effective methods to accurately tune the desired properties.

  17. Sulfolane-Cross-Polybenzimidazole Membrane For Gas Separation

    SciTech Connect

    Young, Jennifer S.; Long, Gregory S.; Espinoza, Brent F.

    2006-02-14

    A cross-linked, supported polybenzimidazole membrane for gas separation is prepared by reacting polybenzimidazole (PBI) with the sulfone-containing crosslinking agent 3,4-dichloro-tetrahydro-thiophene-1,1-dioxide. The cross-linked reaction product exhibits enhanced gas permeability to hydrogen, carbon dioxide, nitrogen, and methane as compared to the unmodified analog, without significant loss of selectivity, at temperatures from about 20 degrees Celsius to about 400 degrees Celsius.

  18. Separation of gas from solvent by membrane technology

    SciTech Connect

    Beaupre, R.F.; Jung, D.Y.

    1991-02-26

    This patent describes the method of separating a charge rich liquid containing gas dissolved in solvent. It comprises: maintaining the charge rich liquid containing gas dissolved in solvent therefore in liquid phase in contact with a gas-permeable, essentially solvent impermeable membrane of pore size of less than about 1000 A and molecular weight cutoff of below about 1,000 selected from the group consisting of cellulose acetate membrane, hydrolyzed cellulose membrane, and polyethyleneimine membrane, and; maintaining a pressure drop across the gas-permeable essentially solvent-impermeable membrane; passing the gas from the charge rich liquid containing gas dissolved in solvent therefore at the higher pressure side of the membrane through the membrane thereby forming lean liquid containing decreased quantities of gas dissolved in solvent on the higher pressure side of the membrane and, on the lower pressure side of the membrane, gas containing decreased quantities of liquid; recovering lean liquid containing decreased quantities of gas dissolved in solvent from the high pressure side of the membrane; and recovering gas containing decreased quantities of liquid from the lower pressure side of the membrane.

  19. Separation of Carbon Dioxide from Flue Gas Using Ion Pumping

    SciTech Connect

    Aines, R; Bourcier, W L; Johnson, M R

    2006-04-21

    We are developing a new way of separating carbon dioxide from flue gas based on ionic pumping of carbonate ions dissolved in water. Instead of relying on large temperature or pressure changes to remove carbon dioxide from solvent used to absorb it from flue gas, the ion pump increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, which can be removed from the downstream side of the ion pump as a nearly pure gas. This novel approach to increasing the concentration of the extracted gas permits new approaches to treating flue gas. The slightly basic water used as the extraction medium is impervious to trace acid gases that destroy existing solvents, and no pre-separation is necessary. The simple, robust nature of the process lends itself to small separation plants. Although the energy cost of the ion pump is significant, we anticipate that it will be compete favorably with the current 35% energy penalty of chemical stripping systems in use at power plants. There is the distinct possibility that this simple method could be significantly more efficient than existing processes.

  20. Inflowing gas onto a compact obscured nucleus in Arp 299A. Herschel spectroscopic studies of H2O and OH

    NASA Astrophysics Data System (ADS)

    Falstad, N.; González-Alfonso, E.; Aalto, S.; Fischer, J.

    2017-01-01

    Aims: We probe the physical conditions in the core of Arp 299A and try to put constraints on the nature of its nuclear power source. Methods: We used Herschel Space Observatory far-infrared and submillimeter observations of H2O and OH rotational lines in Arp 299A to create a multi-component model of the galaxy. In doing this, we employed a spherically symmetric radiative transfer code. Results: Nine H2O lines in absorption and eight in emission, as well as four OH doublets in absorption and one in emission, are detected in Arp 299A. No lines of the 18O isotopologues, which have been seen in compact obscured nuclei of other galaxies, are detected. The absorption in the ground state OH 2Π3/2-2Π3/2(5/2)+-(3/2)- doublet at 119 μm is found redshifted by 175 km s-1 compared with other OH and H2O lines, suggesting a low excitation inflow. We find that at least two components are required in order to account for the excited molecular line spectrum. The inner component has a radius of 20-25 pc, a very high infrared surface brightness (≳3 × 1013L⊙kpc-2), warm dust (Td > 90 K), and a large H2 column density (NH2 > 1024 cm-2). The modeling also indicates high nuclear H2O (1-5 × 10-6) and OH (0.5-5 × 10-5) abundances relative to H nuclei. The outer component is larger (50-100 pc) with slightly cooler dust (70-90 K) and molecular abundances that are approximately one order of magnitude lower. In addition to the two components that account for the excited OH and H2O lines, we require a much more extended inflowing component to account for the OH 2Π3/2-2Π3/2(5/2)+-(3/2)- doublet at 119 μm. Conclusions: The Compton-thick nature of the core makes it difficult to determine the nature of the buried power source, but the high surface brightness indicates that it is an active galactic nucleus and/or a dense nuclear starburst. Our results are consistent with a composite source. The high OH/H2O ratio in the nucleus indicates that ion-neutral chemistry induced by X-rays or

  1. CuO-Decorated ZnO Hierarchical Nanostructures as Efficient and Established Sensing Materials for H2S Gas Sensors

    PubMed Central

    Vuong, Nguyen Minh; Chinh, Nguyen Duc; Huy, Bui The; Lee, Yong-Ill

    2016-01-01

    Highly sensitive hydrogen sulfide (H2S) gas sensors were developed from CuO-decorated ZnO semiconducting hierarchical nanostructures. The ZnO hierarchical nanostructure was fabricated by an electrospinning method following hydrothermal and heat treatment. CuO decoration of ZnO hierarchical structures was carried out by a wet method. The H2S gas-sensing properties were examined at different working temperatures using various quantities of CuO as the variable. CuO decoration of the ZnO hierarchical structure was observed to promote sensitivity for H2S gas higher than 30 times at low working temperature (200 °C) compared with that in the nondecorated hierarchical structure. The sensing mechanism of the hybrid sensor structure is also discussed. The morphology and characteristics of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis absorption, photoluminescence (PL), and electrical measurements. PMID:27231026

  2. A computational chemist approach to gas sensors: modeling the response of SnO2 to CO, O2, and H2O gases.

    PubMed

    Ducéré, Jean-Marie; Hemeryck, Anne; Estève, Alain; Rouhani, Mehdi Djafari; Landa, Georges; Ménini, Philippe; Tropis, Cyril; Maisonnat, André; Fau, Pierre; Chaudret, Bruno

    2012-01-30

    A general bottom-up modeling strategy for gas sensor response to CO, O(2), H(2)O, and related mixtures exposure is demonstrated. In a first stage, we present first principles calculations that aimed at giving an unprecedented review of basic chemical mechanisms taking place at the sensor surface. Then, simulations of an operating gas sensor are performed via a mesoscopic model derived from calculated density functional theory data into a set of differential equations. Significant presence of catalytic oxidation reaction is highlighted.

  3. A study of Zn-Mn based sorbent for the high-temperature removal of H2S from coal-derived gas.

    PubMed

    Ko, Tzu-Hsing; Chu, Hsin; Liou, Ya-Jing

    2007-08-17

    Zn-Mn based sorbents supported on SiO2, gamma-Al(2)O(3) and ZrO2, prepared by the incipient wetness impregnation method with calcination at 973 K were investigated for the removal of H(2)S from coal derived gas at the temperature ranges of 773-973 K. Results reveal that the SiO2 and ZrO2 supports exhibit the better performance because better removal efficiency. The addition of manganese effectually improves the vaporization of zinc. In addition, some operating parameters were also considered in order to understand as well as screen the suitable conditions for the development of Zn-Mn based sorbents on the removal of H(2)S. Over 98% sorbent utilization was established for the use of SiO2 at 873 K. On the other hand, within the 5-15 wt% of Zn-Mn oxides, no significant change in the sorbent utilization was observed. Up to 30 wt% the sorbent utilization decreased slightly compared to lower contents, which may be attributed to the deficient dispersion. With increasing the H2 concentration, the sorbent utilization decreases and an adverse result is observed in the case of increasing CO concentration. The relationship between CO and H2 could be explained via the water-gas shift reaction. Moreover, the apparent activation energy and frequency factor as well as the predicted results were studied with a deactivation model. The results of regression fitting reveal the accurate prediction breakthrough behaviors for the removal of H(2)S.

  4. Process for separating carbon dioxide from flue gas using sweep-based membrane separation and absorption steps

    DOEpatents

    Wijmans, Johannes G.; Baker, Richard W.; Merkel, Timothy C.

    2012-08-21

    A gas separation process for treating flue gases from combustion processes, and combustion processes including such gas separation. The invention involves routing a first portion of the flue gas stream to be treated to an absorption-based carbon dioxide capture step, while simultaneously flowing a second portion of the flue gas across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas to the combustor.

  5. Ligand-modified metal clusters for gas separation and purification

    DOEpatents

    Okrut, Alexander; Ouyang, Xiaoying; Runnebaum, Ron; Gates, Bruce C.; Katz, Alexander

    2017-02-21

    Provided is an organic ligand-bound metal surface that selects one gaseous species over another. The species can be closely sized molecular species having less than 1 Angstrom difference in kinetic diameter. In one embodiment, the species comprise carbon monoxide and ethylene. Such organic ligand-bound metal surfaces can be successfully used in gas phase separations or purifications, sensing, and in catalysis.

  6. Determination of local concentration of H2O molecules and gas temperature in the process of hydrogen - oxygen gas mixture heating by means of linear and nonlinear laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Kozlov, D. N.; Kobtsev, V. D.; Stel'makh, O. M.; Smirnov, Valery V.; Stepanov, E. V.

    2013-01-01

    Employing the methods of linear absorption spectroscopy and nonlinear four-wave mixing spectroscopy using laserinduced gratings we have simultaneously measured the local concentrations of H2O molecules and the gas temperature in the process of the H2 - O2 mixture heating. During the measurements of the deactivation rates of pulsed-laser excited singlet oxygen O2 (b 1Σ+g) in collisions with H2 in the range 294 - 850 K, the joint use of the two methods made it possible to determine the degree of hydrogen oxidation at a given temperature. As the mixture is heated, H2O molecules are formed by 'dark' reactions of H2 with O2 in the ground state. The experiments have shown that the measurements of tunable diode laser radiation absorption along an optical path through the inhomogeneously heated gas mixture in a cell allows high-accuracy determination of the local H2O concentration in the O2 laser excitation volume, if the gas temperature in this volume is known. When studying the collisional deactivation of O2 (b 1Σ+g) molecules, the necessary measurements of the local temperature can be implemented using laser-induced gratings, arising due to spatially periodic excitation of O2 (X3Σ-g) molecules to the b 1Σ+g state by radiation of the pump laser of the four-wave mixing spectrometer.

  7. Synergistic Separation Behavior of Boron in Metallurgical Grade Silicon Using a Combined Slagging and Gas Blowing Refining Technique

    NASA Astrophysics Data System (ADS)

    Wu, Jijun; Zhou, Yeqiang; Ma, Wenhui; Xu, Min; Yang, Bin

    2017-02-01

    A combined slagging and gas blowing refining technique for boron removal from metallurgical grade silicon using the CaO-SiO2-CaCl2 slag and the mixed Ar-O2-H2O gas is investigated. The oxygen gas blowing in combination with water vapor shows a wonderful removal efficiency of boron compared with the single oxygen or the single water vapor blowing. It is analyzed from the thermodynamics that a synergistic separation behavior of boron is resulted from CaCl2 and O2. Boron is removed and reduced from 22 to 0.75 ppmw with a removal efficiency of 96.6 pct.

  8. Separation of Dimethyl Ether from Syn-Gas Components by Poly(dimethylsiloxane) and Poly(4-methyl-1-pentene) Membranes

    SciTech Connect

    Christopher J. Orme; Frederick F. Stewart

    2011-05-01

    Permeability and selectivity in gas transport through poly(4-methyl-1-pentene) (TPX) and poly(dimethylsiloxane) (PDMS) using variable temperature mixed gas experiments is reported. Selected gases include H2, CO, CH4, CO2, and dimethyl ether (DME). The DME data is the first to be reported through these membranes. In this paper, the chosen polymers reflect both rubbery and crystalline materials. Rubbery polymers tend to be weakly size sieving, which, in this work, has resulted in larger permeabilities, lower separation factors, and lower activation energies of permeation (Ep). Conversely, the crystalline TPX membranes showed much greater sensitivity to penetrant size; although the gas condensability also played a role in transport.

  9. Synthesis of ultrasmooth nanostructured diamond films by microwave plasma chemical vapor deposition using a He/H2/CH4/N2 gas mixture

    PubMed Central

    Chowdhury, S.; Hillman, Damon A.; Catledge, Shane A.; Konovalov, Valery V.; Vohra, Yogesh K.

    2008-01-01

    Ultrasmooth nanostructured diamond (USND) films were synthesized on Ti–6Al–4V medical grade substrates by adding helium in H2/CH4/N2 plasma and changing the N2/CH4 gas flow from 0 to 0.6. We were able to deposit diamond films as smooth as 6 nm (root-mean-square), as measured by an atomic force microscopy (AFM) scan area of 2 μm2. Grain size was 4–5 nm at 71% He in (H2 + He) and N2/CH4 gas flow ratio of 0.4 without deteriorating the hardness (~50–60 GPa). The characterization of the films was performed with AFM, scanning electron microscopy, x-ray diffraction (XRD), Raman spectroscopy, and nanoindentation techniques. XRD and Raman results showed the nanocrystalline nature of the diamond films. The plasma species during deposition were monitored by optical emission spectroscopy. With increasing N2/CH4 feedgas ratio (CH4 was fixed) in He/H2/CH4/N2 plasma, a substantial increase of CN radical (normalized by Balmer Hα line) was observed along with a drop in surface roughness up to a critical N2/CH4 ratio of 0.4. The CN radical concentration in the plasma was thus correlated to the formation of ultrasmooth nanostructured diamond films. PMID:18946515

  10. Modeling mass transfer in solid oxide fuel cell anode: II. H2/CO co-oxidation and surface diffusion in synthesis-gas operation

    NASA Astrophysics Data System (ADS)

    Bao, Cheng; Jiang, Zeyi; Zhang, Xinxin

    2016-08-01

    Following the previous work on comparing performance of Fickian, Stefan-Maxwell and dusty-gas model for mass transfer in single fuel system, this article is focused on the electrochemistry and transport in the anode of solid oxide fuel cell using H2sbnd H2Osbnd COsbnd CO2sbnd N2 hybrid fuel. Under the standard framework of the dusty-gas model combined with the Butler-Volmer equation, it carries out a macroscopic area-specific modeling work. More specifically, two variables of hydrogen current fraction and enhancement factor are well defined and solved for the electrochemical co-oxidation of H2 and CO, and the diffusion equivalent circuit model is introduced to describe more comprehensively the resistance of mass transfer including molecular/Knudsen diffusion and surface diffusion. The model has been validated well in full region of Vsbnd I performance of an experimental anode-supported button cell. An approximate analytical solution of the hydrogen current fraction is also presented for explicit computation. Comparison between the results by different approaches for the effective diffusivity shows the importance of right mass-transfer modeling.

  11. A novel flexible C2H2 gas sensor based on Ag-ZnO nanorods on PI/PTFE substrate

    NASA Astrophysics Data System (ADS)

    Uddin, A. S. M. Iftekhar; Chung, Gwiy-Sang

    2016-02-01

    In this work a novel flexible acetylene (C2H2) gas sensor based on Ag nanoparticles decorated vertical ZnO nanorods (Ag-ZnO NRs) on PI/PTFE substrate has been investigated. The grown structure was synthesized through a simple, rapid, and low-temperature hydrothermal-RF magnetron sputtering method. The successful immobilization of Ag nanoparticles (NPs) onto the surface of ZnO nanorods contributed large effective surface area and facilitated the charge transfer process. The as-fabricated sensor exhibited enhanced C2H2 sensing performances at low temperature (200°C) including a broad detection range (3 - 1000 ppm), and short recovery time (39 sec). Mechanical robustness and device flexibility were investigated at different curvature angle (0 - 90°) and several times bending-relaxing process (0 - 5 × 105 times). The sensor exhibited stable response magnitude with a negligible drift of ~ 2.1% for a maximum bending angle of 90o and a response drop of 8% after 5 × 104 bending/relaxing processes. The superior sensing features along with outstanding flexibility to extreme bending stress indicate the sensor a promising candidate for the development of practical flexible C2H2 gas sensors.

  12. Effect of gas phase composition cycling on/off modulation numbers of C2H2/SF6 flows on the formation of geometrically controlled carbon coils.

    PubMed

    Eum, Jun-Ho; Jeon, Young-Chul; Kim, Sung-Hoon

    2012-07-01

    Carbon coils can be synthesized using C2H2/H2 as source gases and SF6 as an incorporated additive gas under a thermal chemical vapor deposition system. In this study, nickel catalyst layer deposition and then hydrogen plasma pretreatment were performed prior to the carbon coils deposition reaction. To obtain geometrically controlled carbon coils, source gases and SF6 were manipulated as the cycling on/off modulation numbers of C2H2/SF6 flows. The cycling numbers were varied according to the different reaction processes. The increased cycling numbers could develop the wave-like nano-sized carbon coils. By further increasing the cycling numbers, however, the nanostructured carbon coils seemed to deteriorate. As a result, the maximum formation of geometrically controlled carbon coils was achieved by adjusting the cycling numbers. The enhanced etching capability of the fluorine-related species in SF6 additive gas was considered for the main objective of controlling the geometry of carbon coils.

  13. Computational study of the I2O5 + H2O = 2 HOIO2 gas-phase reaction

    NASA Astrophysics Data System (ADS)

    Khanniche, Sarah; Louis, Florent; Cantrel, Laurent; Černušák, Ivan

    2016-10-01

    This paper presents the mechanism and the kinetics of the I2O5 (g) + H2O (g) = 2 HOIO2 (g) reaction. The potential energy surface was explored with the B3LYP and MP2 methods with the aug-cc-pVTZ basis set. The rate constants were computed as a function of temperature (250-750 K) using transition state theory. At the CCSD(T)/CBS level, the rate constants were estimated to be: (k in cm3 molecule-1 s-1) kforward(T) = 3.61 × 10-22 × T2.05 exp (-32.3 (kJ mol-1)/RT) and kreverse (T) = 6.73 × 10-27 × T2.90 exp (-24.5 (kJ mol-1)/RT). Implications for atmospheric chemistry and nuclear safety issues are discussed.

  14. Gas adsorption and gas mixture separations using mixed-ligand MOF material

    DOEpatents

    Hupp, Joseph T.; Mulfort, Karen L.; Snurr, Randall Q.; Bae, Youn-Sang

    2011-01-04

    A method of separating a mixture of carbon dioxiode and hydrocarbon gas using a mixed-ligand, metal-organic framework (MOF) material having metal ions coordinated to carboxylate ligands and pyridyl ligands.

  15. BIODESULF(TM), A Novel Biological Technology for the Removal of H2S From Sour Natural Gas

    SciTech Connect

    Srivastava, K.C.; Stashick, J.J.; Johnson, P.E.; Kaushik, N.K.

    1997-10-01

    The state-of-the-art technologies for the removal of sulfur compounds from Sour Natural Gas (SNG) are not cost-effective when scaled down to approximately 2-5 MMSCFD. At the same time, the SNG Production is increasing at 3-6 TCF/Yr and -78 TCF potential reserves are also sour. Assuming only 3% treatment of this potential SNG market is for small volume processing, the potential U.S. Market is worth $0.14 to $0.28 billion. Therefore, the Gas Processing Industry is seeking novel, cost-effective, environmentally compatible and operator friendly technologies applicable to the small volume producers in the range of less than 1 MMSCFD to - 5 MMSCFD. A novel biological process, BIODESTJLFTM (patent pending), developed at ARCTECH removes H{sub 2}S and other sulfur contaminants that make the Natural Gas Sour. The removal is accomplished by utilizing an adapted mixed microbial culture (consortium). A variety of anaerobic microbial consortia from ARCTECH`s Microbial Culture Collection were grown and tested for removal of H{sub 2}S. One of these consortia, termed SS-11 was found to be particularly effective. Utilizing the SS-11 consortium, a process has been developed on a laboratory-scale to remove sulfur species from Sour Natural Gas at well head production pressures and temperatures. The process has been independently evaluated and found to be promising in effectively removing H{sub 2}S and other sulfur species cost effectively.

  16. Laboratory Investigations of a Low-Swirl Injector with H2 and CH4 at Gas Turbine Conditions

    SciTech Connect

    Cheng, R. K.; Littlejohn, D.; Strakey, P.A.; Sidwell, T.

    2008-03-05

    Laboratory experiments were conducted at gas turbine and atmospheric conditions (0.101 < P{sub 0} < 0.810 MPa, 298 < T{sub 0} < 580K, 18 < U{sub 0} < 60 m/s) to characterize the overall behaviors and emissions of the turbulent premixed flames produced by a low-swirl injector (LSI) for gas turbines. The objective was to investigate the effects of hydrogen on the combustion processes for the adaptation to gas turbines in an IGCC power plant. The experiments at high pressures and temperatures showed that the LSI can operate with 100% H{sub 2} at up to {phi} = 0.5 and has a slightly higher flashback tolerance than an idealized high-swirl design. With increasing H{sub 2} fuel concentration, the lifted LSI flame begins to shift closer to the exit and eventually attaches to the nozzle rim and assumes a different shape at 100% H{sub 2}. The STP experiments show the same phenomena. The analysis of velocity data from PIV shows that the stabilization mechanism of the LSI remains unchanged up to 60% H{sub 2}. The change in the flame position with increasing H{sub 2} concentration is attributed to the increase in the turbulent flame speed. The NO{sub x} emissions show a log linear dependency on the adiabatic flame temperature and the concentrations are similar to those obtained previously in a LSI prototype developed for natural gas. These results show that the LSI exhibits the same overall behaviors at STP and at gas turbine conditions. Such insight will be useful for scaling the LSI to operate at IGCC conditions.

  17. The removal of selenate to low ppb levels from flue gas desulfurization brine using the H2-based membrane biofilm reactor (MBfR).

    PubMed

    Van Ginkel, Steven W; Yang, Ziming; Kim, Bi-o; Sholin, Mark; Rittmann, Bruce E

    2011-05-01

    The H(2)-based membrane biofilm reactor (MBfR) was shown to consistently remove nitrate, nitrite, and selenate at high efficiencies from flue-gas desulfurization brine. Selenate was removed to <50 ppb which is the National Pollutant Discharge Elimination System (NPDES) criteria for the brine to be released into the environment. When selenate was removed to <50 ppb, nitrate and nitrite were still present in the mg/L range which suggests that selenate is able to be secondarily reduced to low levels when nitrate and nitrite serve as the main electron acceptors for bacterial growth. SO(4)(2-) was not removed and therefore did not compete with nitrate and selenate reduction for the available H(2).

  18. Computational investigation of thermal gas separation for CO2 capture.

    SciTech Connect

    Gallis, Michail A.; Bryan, Charles R.; Brady, Patrick Vane; Torczynski, John Robert; Brooks, Carlton, F.

    2009-09-01

    This report summarizes the work completed under the Laboratory Directed Research and Development (LDRD) project 09-1351, 'Computational Investigation of Thermal Gas Separation for CO{sub 2} Capture'. Thermal gas separation for a binary mixture of carbon dioxide and nitrogen is investigated using the Direct Simulation Monte Carlo (DSMC) method of molecular gas dynamics. Molecular models for nitrogen and carbon dioxide are developed, implemented, compared to theoretical results, and compared to several experimental thermophysical properties. The molecular models include three translational modes, two fully excited rotational modes, and vibrational modes, whose degree of excitation depends on the temperature. Nitrogen has one vibrational mode, and carbon dioxide has four vibrational modes (two of which are degenerate). These models are used to perform a parameter study for mixtures of carbon dioxide and nitrogen confined between parallel walls over realistic ranges of gas temperatures and nominal concentrations of carbon dioxide. The degree of thermal separation predicted by DSMC is slightly higher than experimental values and is sensitive to the details of the molecular models.

  19. Gas-Phase Synthesis of Boronylallene (H2CCCH(BO)) under Single Collision Conditions: A Crossed Molecular Beams and Computational Study.

    PubMed

    Maity, Surajit; Parker, Dorian S N; Kaiser, Ralf I; Ganoe, Brad; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2014-05-15

    The gas phase reaction between the boron monoxide radical ((11)BO; X(2)Σ(+)) and allene (H2CCCH2; X(1)A1) was investigated experimentally under single collision conditions using the crossed molecular beam technique and theoretically exploiting ab initio electronic structure and statistical (RRKM) calculations. The reaction was found to follow indirect (complex forming) scattering dynamics and proceeded via the formation of a van der Waals complex ((11)BOC3H4). This complex isomerized via addition of the boron monoxide radical ((11)BO; X(2)Σ(+)) with the radical center located at the boron atom to the terminal carbon atom of the allene molecule forming a H2CCCH2(11)BO intermediate on the doublet surface. The chemically activated H2CCCH2(11)BO intermediate underwent unimolecular decomposition via atomic hydrogen elimination from the terminal carbon atom holding the boronyl group through a tight exit transition state to synthesize the boronylallene product (H2CCCH(11)BO) in a slightly exoergic reaction (55 ± 11 kJ mol(-1)). Statistical (RRKM) calculations suggest that minor reaction channels lead to the products 3-propynyloxoborane (CH2((11)BO)CCH) and 1-propynyloxoborane (CH3CC(11)BO) with fractions of 1.5% and 0.2%, respectively. The title reaction was also compared with the cyano (CN; X(2)Σ(+))-allene and boronyl-methylacetylene reactions to probe similarities, but also differences of these isoelectronic systems. Our investigation presents a novel gas phase synthesis and characterization of a hitherto elusive organyloxoborane (RBO) monomer-boronylallene-which is inherently tricky to isolate in the condensed phase except in matrix studies; our work further demonstrates that the crossed molecular beams approach presents a useful tool in investigating the chemistry and synthesis of highly reactive organyloxoboranes.

  20. Ceria-based Catalysts for the Production of H2 Through the Water-gas-shift Reaction: Time-Resolved XRD and XAFS Studies

    SciTech Connect

    Wang,X.; Rodriguez, J.; Hanson, J.; Gamarra, D.; Marinez-Arias, A.; Fernandez-Garcia, M.

    2008-01-01

    Hydrogen is a potential alternate energy source for satisfying many of our energy needs. In this work, we studied H2 production from the water-gas-shift (WGS) reaction over Ce1-x Cu x O2 catalysts, prepared with a novel microemulsion method, using two synchrotron-based techniques: time-resolved X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). The results are compared with those reported for conventional CuO x /CeO2 and AuO x /CeO2 catalysts obtained through impregnation of ceria. For the fresh Ce1-x Cu x O2 catalysts, the results of XAFS measurements at the Cu K-edge indicate that Cu is in an oxidation state higher than in CuO. Nevertheless, under WGS reaction conditions the Ce1-x Cu x O2 catalysts undergo reduction and the active phase contains very small particles of metallic Cu and CeO2-x . Time-resolved XRD and XAFS results also indicate that Cud+ and Aud+ species present in fresh CuO x /CeO2 and AuO x /CeO2 catalysts do not survive above 200 C under the WGS conditions. In all these systems, the ceria lattice displayed a significant increase after exposure to CO and a decrease in H2O, indicating that CO reduced ceria while H2O oxidized it. Our data suggest that H2O dissociation occurred on the Ovacancy sites or the Cu-Ovacancy and Au-Ovacancy interfaces. The rate of H2 generation by a Ce0.95Cu0.05O2 catalyst was comparable to that of a 5 wt% CuO x /CeO2 catalyst and much bigger than those of pure ceria or CuO.

  1. Dynamic Absorption Model for Off-Gas Separation

    SciTech Connect

    Veronica J. Rutledge

    2011-07-01

    Modeling and simulations will aid in the future design of U.S. advanced reprocessing plants for the recovery and recycle of actinides in used nuclear fuel. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, a rate based, dynamic absorption model is being developed in gPROMS software. Inputs include liquid and gas stream constituents, column properties, liquid and gas phase reactions, number of stages, and inlet conditions. It simulates multiple component absorption with countercurrent flow and accounts for absorption by mass transfer and chemical reaction. The assumption of each stage being a discrete well-mixed entity was made. Therefore, the model is solved stagewise. The simulation outputs component concentrations in both phases as a function of time from which the rate of absorption is determined. Temperature of both phases is output as a function of time also. The model will be used able to be used as a standalone model in addition to in series with other off-gas separation unit operations. The current model is being generated based on NOx absorption; however, a future goal is to develop a CO2 specific model. The model will have the capability to be modified for additional absorption systems. The off-gas models, both adsorption and absorption, will be made available via the server or web for evaluation by customers.

  2. The properties of clusters in the gas phase. IV - Complexes of H2O and HNOx clustering on NOx/-/

    NASA Technical Reports Server (NTRS)

    Lee, N.; Castleman, A. W., Jr.; Keesee, R. G.

    1980-01-01

    Thermodynamic quantities for the gas-phase clustering equilibria of NO2(-) and NO3(-) were determined with high-pressure mass spectrometry. A comparison of values of the free energy of hydration derived from the data shows good agreement with formerly reported values at 296 K. New data for larger NO2(-) and NO3(-) hydrates as well as NO2(-)(HNO2)n were obtained in this study. To aid in understanding the bonding and stability of the hydrates of nitrite and nitrate ions, CNDO/2 calculations were performed, and the results are discussed. A correlation between the aqueous-phase total hydration enthalpy of a single ion and its gas-phase hydration enthalpy was obtained. Atmospheric implications of the data are also briefly discussed.

  3. Reactions and Thermochemistry of Alkyl Ions, Cn H2n+1 + (n=1-8), in the Gas Phase

    DTIC Science & Technology

    2007-11-02

    Calcote and Gill48 have recently completed a comp eats and entropies of ionic specie r reliable predictive models for rehensive compilation of the...pp 1755. (3) Calcote, H. F.; Gill, R . J. Comparison of the Ionic Mechanism of Soot Formation with a Free Radical Mechanism; Bockhorn, H., Ed...A. Gas Phase Ion-Molecule Reaction Rate Constants Through 1986; Maruzen Company, Ltd.: Tokyo, 1987. (7) Arnold, S. T.; Viggiano, A. A.; Morris, R . A

  4. Microporous polycarbazole with high specific surface area for gas storage and separation.

    PubMed

    Chen, Qi; Luo, Min; Hammershøj, Peter; Zhou, Ding; Han, Ying; Laursen, Bo Wegge; Yan, Chao-Guo; Han, Bao-Hang

    2012-04-11

    Microporous polycarbazole via straightforward carbazole-based oxidative coupling polymerization is reported. The synthesis route exhibits cost-effective advantages, which are essential for scale-up preparation. The Brunauer-Emmett-Teller specific surface area for obtained polymer is up to 2220 m(2) g(-1). Gas (H(2) and CO(2)) adsorption isotherms show that its hydrogen storage can reach to 2.80 wt % (1.0 bar and 77 K) and the uptake capacity for carbon dioxide is up to 21.2 wt % (1.0 bar and 273 K), which show a promising potential for clean energy application and environmental field. Furthermore, the high selectivity toward CO(2) over N(2) and CH(4) makes the obtained polymer possess potential application in gas separation.

  5. Intracavity CO laser photoacoustic trace gas detection: cyclic CH 4 , H 2 O and CO 2 emission by cockroaches and scarab beetles

    NASA Astrophysics Data System (ADS)

    Bijnen, F. G. C.; Harren, F. J. M.; Hackstein, J. H. P.; Reuss, J.

    1996-09-01

    A liquid-nitrogen-cooled CO laser and an intracavity resonant photoacoustic cell are employed to monitor trace gases. The setup was designed to monitor trace gas emissions of biological samples on line. The arrangement offers the possibility to measure gases at the 10 9 by volume (ppbv) level (e.g., CH 4 , H 2 O) and to detect rapid changes in trace gas emission. A detection limit of 1 ppbv for CH 4 in N 2 equivalent to a minimal detectable absorption of 3 10 9 cm 1 can be achieved. Because of the kinetic cooling effect we lowered the detection limit for CH 4 in air is decreased to 10 ppbv. We used the instrument in a first application to measure the CH 4 and H 2 O emission of individual cockroaches and scarab beetles. These emissions could be correlated with CO 2 emissions that were recorded simultaneously with an infrared gas analyzer. Characteristic breathing patterns of the insects could be observed; unexpectedly methane was also found to be released.

  6. Sturmian theory of three-body recombination: Application to the formation of H2 in primordial gas

    NASA Astrophysics Data System (ADS)

    Forrey, Robert C.

    2013-11-01

    A Sturmian theory of three-body recombination is presented which provides a unified treatment of bound states, quasibound states, and continuum states. The Sturmian representation provides a numerical quadrature of the two-body continuum which may be used to generate a complete set of states within any desired three-body recombination pathway. Consequently, the dynamical calculation may be conveniently formulated using the simplest energy transfer mechanism, even for reactive systems which allow substantial rearrangement. The Sturmian theory generalizes the quantum kinetic theory of Snider and Lowry [J. Chem. Phys.10.1063/1.1682310 61, 2330 (1974)] to include metastable states which are formed as independent species. Steady-state rate constants are expressed in terms of a pathway-independent part plus a nonequilibrium correction which depends on tunneling lifetimes and pressure. Numerical results are presented for H2 recombination due to collisions with H and He using quantum-mechanical coupled states and infinite-order sudden approximations. These results may be used to remove some of the uncertainties that have limited astrophysical simulations of primordial star formation.

  7. Nanostructured PdO Thin Film from Langmuir-Blodgett Precursor for Room-Temperature H2 Gas Sensing.

    PubMed

    Choudhury, Sipra; Betty, C A; Bhattacharyya, Kaustava; Saxena, Vibha; Bhattacharya, Debarati

    2016-07-06

    Nanoparticulate thin films of PdO were prepared using the Langmuir-Blodgett (LB) technique by thermal decomposition of a multilayer film of octadecylamine (ODA)-chloropalladate complex. The stable complex formation of ODA with chloropalladate ions (present in subphase) at the air-water interface was confirmed by the surface pressure-area isotherm and Brewster angle microscopy. The formation of nanocrystalline PdO thin film after thermal decomposition of as-deposited LB film was confirmed by X-ray diffraction and Raman spectroscopy. Nanocrystalline PdO thin films were further characterized by using UV-vis and X-ray photoelectron spectroscopic (XPS) measurements. The XPS study revealed the presence of prominent Pd(2+) with a small quantity (18%) of reduced PdO (Pd(0)) in nanocrystalline PdO thin film. From the absorption spectroscopic measurement, the band gap energy of PdO was estimated to be 2 eV, which was very close to that obtained from specular reflectance measurements. Surface morphology studies of these films using atomic force microscopy and field-emission scanning electron microscopy indicated formation of nanoparticles of size 20-30 nm. These PdO film when employed as a chemiresistive sensor showed H2 sensitivity in the range of 30-4000 ppm at room temperature. In addition, PdO films showed photosensitivity with increase in current upon shining of visible light.

  8. Thermophoretic separation of aerosol particles from a sampled gas stream

    DOEpatents

    Postma, A.K.

    1984-09-07

    This disclosure relates to separation of aerosol particles from gas samples withdrawn from within a contained atmosphere, such as containment vessels for nuclear reactors or other process equipment where remote gaseous sampling is required. It is specifically directed to separation of dense aerosols including particles of any size and at high mass loadings and high corrosivity. The United States Government has rights in this invention pursuant to Contract DE-AC06-76FF02170 between the US Department of Energy and Westinghouse Electric Corporation.

  9. Reduction of Sn-Bearing Iron Concentrate with Mixed H2/CO Gas for Preparation of Sn-Enriched Direct Reduced Iron

    NASA Astrophysics Data System (ADS)

    You, Zhixiong; Li, Guanghui; Wen, Peidan; Peng, Zhiwei; Zhang, Yuanbo; Jiang, Tao

    2017-02-01

    The development of manufacturing technology of Sn-bearing stainless steel inspires a novel concept for using Sn-bearing complex iron ore via reduction with mixed H2/CO gas to prepare Sn-enriched direct reduced iron (DRI). The thermodynamic analysis of the reduction process confirms the easy reduction of stannic oxide to metallic tin and the rigorous conditions for volatilizing SnO. Although the removal of tin is feasible by reduction of the pellet at 1223 K (950 °C) with mixed gas of 5 vol pct H2, 28.5 vol pct CO, and 66.5 vol pct CO2 (CO/(CO + CO2) = 30 pct), it is necessary that the pellet be further reduced for preparing DRI. In contrast, maintaining Sn in the metallic pellet is demonstrated to be a promising way to effectively use the ore. It is indicated that only 5.5 pct of Sn is volatilized when the pellet is reduced at 1223 K (950 °C) for 30 minutes with the mixed gas of 50 vol pct H2, 50 vol pct CO (CO/(CO + CO2) = 100 pct). A metallic pellet (Sn-bearing DRI) with Sn content of 0.293 pct, Fe metallization of 93.5 pct, and total iron content of 88.2 pct is prepared as a raw material for producing Sn-bearing stainless steel. The reduced tin in the Sn-bearing DRI either combines with metallic iron to form Sn-Fe alloy or it remains intact.

  10. Gas separation and bubble behavior at a woven screen

    NASA Astrophysics Data System (ADS)

    Conrath, Michael; Dreyer, Michael E.

    Gas-liquid two phase flows are widespread and in many applications the separation of both phases is necessary. Chemical reactors, water treatment devices or gas-free delivery of liquids like propellant are only some of them. We study the performance of a woven metal screen in respect to its phase separation behavior under static and dynamic conditions. Beside hydraulic screen resistance and static bubble point, our study also comprises the bubble detachment from the screen upon gas breakthrough. Since a woven screen is essentially an array of identical pores, analogies to bubble detachment from a needle can be established. While the bubble point poses an upper limit for pressurized gas at a wetted screen to preclude gas breakthrough, the necessary pressure for growing bubbles to detach from the screen pores a lower limit when breakthrough is already in progress. Based on that inside, the dynamic bubble point effects were constituted that relate to a trapped bubble at such a screen in liquid flow. A trapped is caused to break through the screen by the flow-induced pressure drop across it. Our model includes axially symmetric bubble shapes, degree of coverage of the screen and bubble pressurization due to hydraulic losses in the rest of the circuit. We have built an experiment that consists of a Dutch Twilled woven screen made of stainless steel in a vertical acrylic glass tube. The liquid is silicon oil SF0.65. The screen is suspended perpendicular to the liquid flow which is forced through it at variable flow rate. Controlled injection of air from a needle allows us to examine the ability of the screen to separate gas and liquid along the former mentioned effects. We present experimental data on static bubble point and detachment pressure for breakthrough at different gas supply rates that suggest a useful criterion for reliable static bubble point measurements. Results for the dynamic bubble point are presented that include i) screen pressure drop for different

  11. Morphology, luminescence, and electrical resistance response to H 2 and CO gas exposure of porous InP membranes prepared by electrochemistry in a neutral electrolyte

    NASA Astrophysics Data System (ADS)

    Volciuc, O.; Monaico, E.; Enachi, M.; Ursaki, V. V.; Pavlidis, D.; Popa, V.; Tiginyanu, I. M.

    2010-11-01

    Porous InP membranes have been prepared by anodization of InP wafers with electron concentration of 1 × 10 17 cm -3 and 1 × 10 18 cm -3 in a neutral NaCl electrolyte. The internal surfaces of pores in some membranes were modified by electrochemical deposition of gold in a pulsed voltage regime. Photoluminescence and photosensitivity measurements indicate efficient light trapping and porous surface passivation. The photoluminescence and electrical resistivity of the membranes are sensitive to the adsorption of H 2 and CO gas molecules. These properties are also influenced by the deposition of Au nanoparticles inside the pores.

  12. Using Continuous Monitoring of Ambient CO2 and H2S to Assess Toxic Gas Hazards in Yellowstone National Park, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Elias, T.; Sutton, A.; Lowenstern, J.; Heasler, H.; Eagan, S.

    2007-12-01

    The mysterious death of five bison in the Norris Geyser Basin area of Yellowstone in 2004 was apparently due to an increase in the output of CO2 or H2S, coupled with unusually cold, still weather. This event of nature may support a long-held claim of geochemists: near-surface changes in pressure, temperature, hydrologic flow, ground permeability, and wind conditions can reasonably be expected to produce attendant variability in the output and ambient concentration of gases emitted from hydrothermal areas. Monitoring these changes at the surface provides a window to processes occurring below, and a continuous assessment of gas hazards for frequently visited places like Norris. To characterize subsurface processes and identify hazards, we developed a transportable monitoring system to measure ambient gas concentrations and meteorological parameters. The solar-powered system uses industrial grade sensors for CO2 and H2S gas, along with sensors for wind speed and direction, barometric pressure, and ambient temperature. In order to reduce power use and prolong sensor life, every 10-minutes the gas sensors are powered on and allowed to stabilize, and the average values for the gas and met sensors are then recorded. The system can be configured for on-site data logging or radio telemetry. During the first year of operation in a thermal area adjacent to where the bison died, the system recorded diurnal variations. Although CO2 build-up was observed at night during cool windless conditions, ambient concentrations of CO2 and H2S remained below hazardous levels. Encouraged by the robust performance of the sensors, a second system was built to use as a roving monitor within the park as conditions permit and opportunities arise to track thermal variations. The performance of this system during the first year of operation reinforces the importance of continuous monitoring for processes such as gas-release events. Such occurrences, while evidenced in nature by events like the

  13. Simulation of the growth kinetics of boride layers formed on Fe during gas boriding in H2-BCl3 atmosphere

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Makuch, N.; Pertek, A.; Małdziński, L.

    2013-03-01

    The modeling of the boriding kinetics is considered as a necessary tool to select the suitable process parameters for obtaining boride layer of an adequate thickness. Therefore, the simulation of the growth kinetics of boride layers has gained much attention for last years. The majority of the published works described the kinetics of the pack-boriding or paste-boriding. In this study, the model of growth kinetics of two-phase boride layer (FeB+Fe2B) on pure Fe was proposed for gas boriding. Displacements of the two interfaces (FeB/Fe2B and Fe2B/substrate) resulted from a difference of the arrival flux of interstitial boron atoms to one phase and the departure flux of the boron atoms from this phase to the second phase. The mass balance equations were formulated. The measurements of thickness of both zones (FeB and Fe2B), for different temperature of boriding, were used for calculations. Based on the experimental data, the parabolic growth constants AFeB and B versus the temperature of boriding were determined. The linear relationships were accepted. As a consequence, the activation energies (QFeB and Q) were calculated. The calculated values were comparable to other data derived from gas boriding. The presented model can predict the thicknesses of the FeB and Fe2B zones (XFeB and Y, respectively) formed on pure Fe during gas boriding. Additionally, the diffusion annealing after boriding was analyzed. This process was carried out in order to obtain a single-phase boride layer (Fe2B). The relationship between the reduction in FeB zone (dXFeB) and the growth in Fe2B phase (dY) was determined. The time tXFeB=0, needed for the total elimination of FeB phase in the boride layer was calculated and compared to the experimental data.

  14. Rare-gas-rich separates from carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Reynolds, J. H.; Frick, U.; Neil, J. M.; Phinney, D. L.

    1978-01-01

    This paper describes an analysis of carbon-rich separates prepared by demineralization of colloidal fractions after disaggregation of bulk samples of the type C2 meteorites Murray, Murchison, and Cold Bokkeveld, as well as a methanol colloid extracted from acid-resistant residues of the Allende meteorite (type C3V) obtained by dissolution of most of the minerals in HCl and HF acids. The carbonaceous separates, or lAlates (a coined word designating colloids prepared sometimes before and sometimes after acid treatment), are characterized incompletely and with difficulty. A stepwise heating experiment on a Murray lAlate is discussed which revealed bimodal release of all noble gases, with similar patterns for Ar, Kr, and Xe. Chemical reactions are suggested as the likely mechanism for gas release. The results are shown to support the concept of a carbonaceous gas carrier uniformly present in meteorites of various types.

  15. Gas separation device based on electrical swing adsorption

    DOEpatents

    Judkins, Roddie R.; Burchell, Timothy D.

    1999-10-26

    A method and apparatus for separating one constituent, especially carbon dioxide, from a fluid mixture, such as natural gas. The fluid mixture flows through an adsorbent member having an affinity for molecules of the one constituent, the molecules being adsorbed on the adsorbent member. A voltage is applied to the adsorbent member, the voltage imparting a current flow which causes the molecules of the one constituent to be desorbed from the adsorbent member.

  16. Carbon-fiber composite molecular sieves for gas separation

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.; Fei, Y.Q.

    1995-08-01

    The progress of research in the development of novel, rigid, monolithic adsorbent carbon fiber composites is described. Carbon fiber composites are produced at ORNL and activated at the CAER using steam or CO{sub 2} under different conditions, with the aims of producing a uniform degree of activation through the material, and of closely controlling pore structure and adsorptive properties The principal focus of the work to date has been to produce materials with narrow porosity for use in gas separations.

  17. Ion-Gated Gas Separation through Porous Graphene.

    PubMed

    Tian, Ziqi; Mahurin, Shannon M; Dai, Sheng; Jiang, De-En

    2017-03-08

    Porous graphene holds great promise as a one-atom-thin, high-permeance membrane for gas separation, but to precisely control the pore size down to 3-5 Å proves challenging. Here we propose an ion-gated graphene membrane comprising a monolayer of ionic liquid-coated porous graphene to dynamically modulate the pore size to achieve selective gas separation. This approach enables the otherwise nonselective large pores on the order of 1 nm in size to be selective for gases whose diameters range from 3 to 4 Å. We show from molecular dynamics simulations that CO2, N2, and CH4 all can permeate through a 6 Å nanopore in graphene without any selectivity. But when a monolayer of [emim][BF4] ionic liquid (IL) is deposited on the porous graphene, CO2 has much higher permeance than the other two gases. We find that the anion dynamically modulates the pore size by hovering above the pore and provides affinity for CO2, while the larger cation (which cannot go through the pore) holds the anion in place via electrostatic attraction. This composite membrane is especially promising for CO2/CH4 separation, yielding a CO2/CH4 selectivity of about 42 and CO2 permeance of ∼10(5) GPU (gas permeation unit). We further demonstrate that selectivity and permeance can be tuned by the anion size, pore size, and IL thickness. The present work points toward a promising direction of using the atom-thin ionic liquid/porous graphene hybrid membrane for high-permeance, selective gas separation that allows a greater flexibility in substrate pore size control.

  18. Ion-Gated Gas Separation through Porous Graphene

    DOE PAGES

    Tian, Ziqi; Mahurin, Shannon M.; Dai, Sheng; ...

    2017-02-10

    Porous graphene holds great promise as an atom-thin, high-permeance membrane for gas separation, but to precisely control the pore size at three to five angstroms proves challenging. Here we propose an ion-gated graphene membrane comprising a monolayer of ionic liquid coated porous graphene to dynamically modulate the pore size to achieve selective gas separation. This approach enables the otherwise non-selective large pores on the order of 1 nm in size to be selective for gases whose diameters range from three to four angstroms. We show from molecular dynamics simulations that CO2, N2 and CH4 all can permeate through a 1-nmmore » pore in graphene without any selectivity. But when a monolayer of [emim][BF4] is deposited on the porous graphene, CO2 has much higher permeance than the other two gases. We find that the anion dynamically modulates the pore size by hovering above the pore and provides affinity for CO2 while the larger cation (which cannot go through the pore) holds the anion in place via electrostatic attraction. This composite membrane is especially promising for CO2/CH4 separation, with a CO2/CH4 selectivity of about 42 and CO2 permeance ~105 GPU (gas permeation unit). We further demonstrate that selectivity and permeance can be tuned by the anion size. The present work points toward a promising direction of using the atom-thin ionic-liquid/porous-graphene hybrid membrane for high-permeance, selective gas separation that allows a greater flexibility in substrate pore size control.« less

  19. Absolute density of precursor SiH3 radicals and H atoms in H2-diluted SiH4 gas plasma for deposition of microcrystalline silicon films

    NASA Astrophysics Data System (ADS)

    Abe, Yusuke; Ishikawa, Kenji; Takeda, Keigo; Tsutsumi, Takayoshi; Fukushima, Atsushi; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

    2017-01-01

    Microcrystalline hydrogenated silicon films were produced at a high deposition rate of about 2 nm/s by using a capacitively coupled plasma under a practical pressure of around 1 kPa. The SiH4 source gas was almost fully dissociated when highly diluted with H2 gas, and the dominant species in the gas phase were found to be SiH3 radicals, which are film-growth precursors, and H atoms. The absolute density of these species was measured as the partial pressure of SiH4 gas was varied. With the increasing SiH4 gas flow rate, the SiH3 radical density, which was on the order of 1012 cm-3, increased linearly, while the H-atom density remained constant at about 1012 cm-3. The film growth mechanism was described in terms of precursors, based on the measured flux of SiH3 radicals and H atoms, and the relative fraction of higher-order radicals.

  20. Task 6.5 - Gas Separation and Hot-Gas Cleanup

    SciTech Connect

    Swanson, Michael L.; Ness Jr., Robert O.; Hurley, John P.; McCollor, Donald P.

    1997-06-01

    Catalytic gasification of coal to produce H{sub 2}- and CH{sub 4}-rich gases for consumption in molten carbonate fuel cells is currently under development; however, to optimize the fuel cell performance and extend its operating life, it is desired to separate as much of the inerts (i.e., CO{sub 2} and N{sub 2}) and impurities (i.e., H{sub 2}S and NH{sub 3}) as possible from the fuel gas before they enter the fuel cell. In addition, the economics of the integrated gasification combined cycle (IGCC) can be improved by separating as much of the hydrogen as possible from the fuel, since hydrogen is a high-value product. One process currently under development by the Energy & Environmental Research Center (EERC) for accomplishing this gas separation and hot-gas cleanup involves gas separation membranes. These membranes are operated at temperatures as high as 800 C and pressures up to 300 psig. Some of these membranes can have very small pores (30-50 {angstrom}), which inefficiently separate the undesired gases by operating in the Knudsen diffusion region of mass transport. Other membranes with smaller pore sizes (<5 {angstrom}) operate in the molecular sieving region of mass transport phenomena, Dissolution of atomic hydrogen into thin metallic membranes made of platinum and palladium alloys is also being developed. Technological and economic issues that must be resolved before gas separation membranes are commercially viable include improved gas separation efficiency, membrane optimization, sealing of membranes in pressure vessels, high burst strength of the ceramic material, pore thermal stability, and material chemical stability. Hydrogen separation is dependent on the temperature, pressure, pressure ratio across the membrane, and ratio of permeate flow to total flow. For gas separation under Knudsen diffusion, increasing feed pressure and pressure ratio across the membrane should increase gas permeability; decreasing the temperature and the permeate-to-total flow

  1. Optimization of an enclosed gas analyzer sampling system for measuring eddy covariance fluxes of H2O and CO2

    DOE PAGES

    Metzger, Stefan; Burba, George; Burns, Sean P.; ...

    2016-03-31

    Several initiatives are currently emerging to observe the exchange of energy and matter between the earth's surface and atmosphere standardized over larger space and time domains. For example, the National Ecological Observatory Network (NEON) and the Integrated Carbon Observing System (ICOS) are set to provide the ability of unbiased ecological inference across ecoclimatic zones and decades by deploying highly scalable and robust instruments and data processing. In the construction of these observatories, enclosed infrared gas analyzers are widely employed for eddy covariance applications. While these sensors represent a substantial improvement compared to their open- and closed-path predecessors, remaining high-frequency attenuation variesmore » with site properties and gas sampling systems, and requires correction. Here, we show that components of the gas sampling system can substantially contribute to such high-frequency attenuation, but their effects can be significantly reduced by careful system design. From laboratory tests we determine the frequency at which signal attenuation reaches 50 % for individual parts of the gas sampling system. For different models of rain caps and particulate filters, this frequency falls into ranges of 2.5–16.5 Hz for CO2, 2.4–14.3 Hz for H2O, and 8.3–21.8 Hz for CO2, 1.4–19.9 Hz for H2O, respectively. A short and thin stainless steel intake tube was found to not limit frequency response, with 50 % attenuation occurring at frequencies well above 10 Hz for both H2O and CO2. From field tests we found that heating the intake tube and particulate filter continuously with 4 W was effective, and reduced the occurrence of problematic relative humidity levels (RH > 60 %) by 50 % in the infrared gas analyzer cell. No further improvement of H2O frequency response was found for heating in excess of 4 W. These laboratory and field tests were reconciled using resistor–capacitor theory, and NEON's final gas sampling system was

  2. Sulfur-doped graphene via thermal exfoliation of graphite oxide in H2S, SO2, or CS2 gas.

    PubMed

    Poh, Hwee Ling; Šimek, Petr; Sofer, Zdeněk; Pumera, Martin

    2013-06-25

    Doping of graphene with heteroatoms is an effective way to tailor its properties. Here we describe a simple and scalable method of doping graphene lattice with sulfur atoms during the thermal exfoliation process of graphite oxides. The graphite oxides were first prepared by Staudenmaier, Hofmann, and Hummers methods followed by treatments in hydrogen sulfide, sulfur dioxide, or carbon disulfide. The doped materials were characterized by scanning electron microscopy, high-resolution X-ray photoelectron spectroscopy, combustible elemental analysis, and Raman spectroscopy. The ζ-potential and conductivity of sulfur-doped graphenes were also investigated in this paper. It was found that the level of doping is more dramatically influenced by the type of graphite oxide used rather than the type of sulfur-containing gas used during exfoliation. Resulting sulfur-doped graphenes act as metal-free electrocatalysts for an oxygen reduction reaction.

  3. Application of a gas-solid fluidized bed separator for shredded municipal bulky solid waste separation.

    PubMed

    Sekito, T; Matsuto, T; Tanaka, N

    2006-01-01

    A laboratory-scale gas-solid fluidized bed separator able to separate fractions of 5.6-50mm was used for separation of shredded municipal bulky waste (SBW) into combustibles and incombustibles. In batch-scale tests, it was found that accumulation of SBW in the bottom of the bed significantly reduced the separation efficiency. In this study, stirring was shown to be effective in preventing this accumulation. Flexible sheet materials such as paper and film plastics also significantly decreased the separation efficiency. In batch-scale tests, an overall efficiency of 90% was obtained when flexible materials such as film plastics and paper were excluded from the feed SBW. In continuous feeding tests, purities of the float and sink fractions attained 95% and 86% efficiencies, respectively, with an overall efficiency of 79%. The effect of feedstock shape on separation efficiency was also investigated. This study revealed that large particles can be properly separated on the basis of density, while the shape of the material significantly influenced behavior in the fluidizing bed.

  4. Use of exhaust gas as sweep flow to enhance air separation membrane performance

    DOEpatents

    Dutart, Charles H.; Choi, Cathy Y.

    2003-01-01

    An intake air separation system for an internal combustion engine is provided with purge gas or sweep flow on the permeate side of separation membranes in the air separation device. Exhaust gas from the engine is used as a purge gas flow, to increase oxygen flux in the separation device without increasing the nitrogen flux.

  5. Possible gas-phase reactions of H2/CH4/tetramethylsilane in diamond/beta-SiC nanocomposite film deposition: an ab-initio study.

    PubMed

    Zhao, Y L; Zhang, R Q; Srikanth, Vadali V S S; Jiang, X

    2007-05-10

    The Si-C bond breakings in tetramethylsilane (TMS) when interacting with H/H2 and the successive H abstractions from SiH4/CH4 in the gas mixture of H2/ CH4/TMS were studied at the CCSD(T)/6-311+G**//MP2/6-31+G** level of theory. Their rate constants between 1500 and 2500 K were estimated using a conventional transition state theory. The results indicate that (i) it is mainly the H radical that causes the Si-C bond breaking in TMS, and (ii) the successive H abstractions from SiH4 are much easier and faster than those from CH4. At low temperatures the differences of rate constants among the four types of the reactions are large, but generally reduced at high temperatures. The reaction rates show no selectivity over the pressure as verified at P = 0.00025, 0.025, 1, and 100 atm, respectively. Our results could provide the following microscopic level understanding of reactions in the synthesis of diamond/beta-SiC nanocomposite films. Although the Si content is smaller than that of C in the precursor gases, the gas mixture activated by microwave plasma technique could provide Si sources with a higher rate. The produced Si sources with excellent rigidity in sp3 hybridization competitively occupy the space on the substrate together with C sources, resulting in the deposition of diamond/beta-SiC nanocomposite films.

  6. Study of low-defect and strain-relaxed GeSn growth via reduced pressure CVD in H2 and N2 carrier gas

    NASA Astrophysics Data System (ADS)

    Margetis, J.; Mosleh, A.; Al-Kabi, S.; Ghetmiri, S. A.; Du, W.; Dou, W.; Benamara, M.; Li, B.; Mortazavi, M.; Naseem, H. A.; Yu, S.-Q.; Tolle, J.

    2017-04-01

    High quality, thick (up to 1.1 μm), strain relaxed GeSn alloys were grown on Ge-buffered Si (1 0 0) in an ASM Epsilon® chemical vapor deposition system using SnCl4 and low-cost commercial GeH4 precursors. The significance of surface chemistry in regards to growth rate and Sn-incorporation is discussed by comparing growth kinetics data in H2 and N2 carrier gas. The role of carrier gas is also explored in the suppression of Sn surface segregation and evolution of layer composition and strain profiles via secondary ion mass spectrometry and X-ray diffraction. Transmission electron microscopy revealed the spontaneous compositional splitting and formation of a thin intermediate layer in which dislocations are pinned. This intermediate layer enables the growth of a thick, strain relaxed, and defect-free epitaxial layer on its top. Last, we present photoluminescence results which indicate that both N2 and H2 growth methods produce optoelectronic device quality material.

  7. Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by H2 SO4 and CO2 Gas for Supercapacitor

    NASA Astrophysics Data System (ADS)

    Deraman, M.; Ishak, M. M.; Farma, R.; Awitdrus, Taer, E.; Talib, I. A.; Omar, R.

    2011-12-01

    Binderless composite electrodes in the monolithic form prepared from carbon nanotubes (CNTs) and self-adhesive carbon grains (SACG) from fibers of oil palm empty fruit bunch were studied as an electrode in a supercapacitor. The green monoliths (GMs) were prepared from three different types of precursors, SACG, SACG treated with 0.4 Molar H2 SO4 and mixture of SACG and 5% CNTs (by weight) treated with 0.4 Molar H2 SO4 , respectively. These GMs were carbonized at 600 ° C in N2 gas environment and activated by CO2 gas at 800 ° C for 1 hour to produce activated carbon monoliths (ACMs). The properties of the ACMs (density, porosity, microstructure, structure and electrical conductivity) were found affected by CNTs addition and acid treatment. The acid treatment did not improve the electrochemical behavior of the ACMs used as electrodes (specific capacitance, specific energy and specific power of the supercapacitor) in the supercapacitor cells but CNTs addition improves the equivalent series resistance of the cell.

  8. Recombination of H+3 ions with electrons in He/H2 ambient gas at temperatures from 240 K to 340 K

    NASA Astrophysics Data System (ADS)

    Glosík, J.; Dohnal, P.; Rubovič, P.; Kálosi, Á.; Plašil, R.; Roučka, Š.; Johnsen, R.

    2015-12-01

    We have studied the recombination of \\text{H}3+ ions with electrons in a stationary afterglow experiment either in pure hydrogen or in mixtures of helium, hydrogen, and argon. The decay of the ion density during the afterglow was monitored using near-infrared cavity ring-down absorption spectroscopy. The gas temperatures ranged from 240 K to 340 K. We find that three-body recombination, where molecular hydrogen acts as a third body, increases the recombination rate significantly. However, {{\\text{H}}2} assisted three-body recombination saturates at hydrogen densities above ≈ {{10}16}~\\text{c}{{\\text{m}}-3} and the recombination rate then becomes nearly independent of the neutral gas density. The saturation can lead to the erroneous conclusion that the recombination is purely binary and this appears to be the cause of some inconsistencies between previously reported recombination rate coefficients. At temperatures 240-340 K the obtained three-body recombination rate coefficient is independent on temperature ({{K}\\text{H2}}=≤ft(9.4~+/- ~1.3\\right)× {{10}-23}~\\text{c}{{\\text{m}}6}~{{\\text{s}}-1} ) and it is larger by five orders of magnitude than those expected from the classical theory for atomic ions of Bates and Khare ({{K}\\text{BK}}≤ft(300~\\text{K}\\right)≈ {{10}-27}~\\text{c}{{\\text{m}}6}~{{\\text{s}}-1} ). The observed dependences on {{\\text{H}}2} density suggest that a substantial fraction of neutral \\text{H}3\\# complexes formed in capture of electrons by \\text{H}3+ ions do not rapidly predissociate but can be stabilized by interactions with third bodies. Saturation occurs if the capture step is rate limiting rather than stabilization.

  9. Isotope fractionation in aqua-gas systems: Cl(2)-HCl-Cl(-), Br(2)-HBr-Br(-) and H(2)S-S(2-).

    PubMed

    Czarnacki, Maciej; Hałas, Stanisław

    2012-01-01

    We report calculated values of isotope fractionation factors between chlorine, bromine and sulphide hydrated anions and respective gaseous compounds: hydrogen chloride, hydrogen bromide, molecular chlorine and bromine and hydrogen sulphide. For the calculation of the reduced partition function ratios (β-factors) of hydrated Cl(-), Br(-) and S(2-) anions, we used a model of a cluster composed of the considered ion surrounded by two shells of H(2)O molecules. Only the electrostatic interaction between ion and water molecules treated as electric dipoles was taken into account. The β-factors for the gaseous compounds (HCl, Cl(2), HBr, Br(2) and H(2)S) were calculated from vibrational frequencies reported by Urey and Greiff [Isotopic Exchange Equilibria, J. Am. Chem. Soc. 57, 321 (1935)] and Schauble et al. [Theoretical Estimates Equilibrium Chlorine-Isotope Fractionation, Geochim. Cosmochim. Acta 67, 3267 (2003)]. Low-temperature isotope fractionation between chlorine-hydrated anion and hydrogen chloride attains 1.55-1.68‰ (this work), which is in good agreement with experimental data (1.4-1.8‰) [Z.D. Sharp, J.D. Barnes, T.P. Fischer and M. Halick, An Experimental Determination of Chlorine Isotope Fractionation in Acid Systems and Applications to Volcanic Fumaroles, Geochim. Cosmochim. Acta 74, 264 (2010)]. The predicted isotope fractionations for hydrated bromine and HBr, Br(2) gases are very small, 1000 ln α, do not exceed 0.8‰; thus, the expected variations of bromine isotope composition in aqua-gas systems will require enhanced precision for their detection. In contrast, the sulphur isotope fractionation between H(2)S( gas ) and S(2-) attains 6.0‰ at room temperature and drops nearly linearly to 3.1‰ at 350°C.

  10. Separation of CO2 from flue gas using electrochemical cells

    SciTech Connect

    Pennline, H.W; Granite, E.J.; Luebke, D.R; Kitchin, J.R; Landon, J.; Weiland, L.M.

    2010-06-01

    ABSTRACT Past research with high temperature molten carbonate electrochemical cells has shown that carbon dioxide can be separated from flue gas streams produced by pulverized coal combustion for power generation, However, the presence of trace contaminants, i.e" sulfur dioxide and nitric oxides, will impact the electrolyte within the cell. If a lower temperature cell could be devised that would utilize the benefits of commercially-available, upstream desulfurization and denitrification in the power plant, then this CO2 separation technique can approach more viability in the carbon sequestration area, Recent work has led to the assembly and successful operation of a low temperature electrochemical cell. In the proof-of-concept testing with this cell, an anion exchange membrane was sandwiched between gas-diffusion electrodes consisting of nickel-based anode electrocatalysts on carbon paper. When a potential was applied across the cell and a mixture of oxygen and carbon dioxide was flowed over the wetted electrolyte on the cathode side, a stream of CO2 to O2 was produced on the anode side, suggesting that carbonate/ bicarbonate ions are the CO2 carrier in the membrane. Since a mixture of CO 2 and 02 is produced, the possibility exists to use this stream in oxy-firing of additional fuel. From this research, a novel concept for efficiently producing a carbon dioxide rich effiuent from combustion of a fossil fuel was proposed. Carbon dioxide and oxygen are captured from the flue gas of a fossilfuel combustor by one or more electrochemical cells or cell stacks. The separated stream is then transferred to an oxy-fired combustor which uses the gas stream for ancillary combustion, ultimately resulting in an effluent rich in carbon dioxide, A portion of the resulting flow produced by the oxy-fired combustor may be continuously recycled back into the oxy-fired combustor for temperature control and an optimal carbon dioxide rich effluent.

  11. Separation of flue-gas scrubber sludge into marketable products

    SciTech Connect

    Kawatra, S.K.; Eisele, T.C.

    1997-08-31

    A tremendous amount of wet flue-gas desulfurization scrubber sludge (estimated 20 million metric tons per year in the US) is currently being landfilled at a huge cost to utility companies. Scrubber sludge is the solid precipitate produced during desulfurization of flue-gas from burning high sulfur coal. The amount of this sludge is expected to increase in the near future due to ever increasing governmental regulation concerning the amount of sulfur emissions. Scrubber sludge is a fine, grey colored powder that contains calcium sulfite hemihydrate (CaSO{sub 3} {center_dot} 1/2H{sub 2}), calcium sulfate dihydrate (CaSO{sub 4} {center_dot} 2H{sub 2}O), limestone (CaCO{sub 3}), silicates, and iron oxides. This material can continue to be landfilled at a steadily increasing cost, or an alternative for utilizing this material can be developed. This study explores the characteristics of a naturally oxidized wet flue-gas desulfurization scrubber sludge and uses these characteristics to develop alternatives for recycling this material. In order for scrubber sludge to be used as a feed material for various markets, it was necessary to process it to meet the specifications of these markets. A physical separation process was therefore needed to separate the components of this sludge into useful products at a low cost. There are several physical separation techniques available to separate fine particulates. These techniques can be divided into four major groups: magnetic separation, electrostatic separation, physico-chemical separation, and density-based separation. The properties of this material indicated that two methods of separation were feasible: water-only cycloning (density-based separation), and froth flotation (physico-chemical separation). These processes could be used either separately, or in combination. The goal of this study was to reduce the limestone impurity in this scrubber sludge from 5.6% by weight to below 2.0% by weight. The resulting clean calcium

  12. First detection of gas-phase ammonia in a planet-forming disk. NH3, N2H+, and H2O in the disk around TW Hydrae

    NASA Astrophysics Data System (ADS)

    Salinas, Vachail N.; Hogerheijde, Michiel R.; Bergin, Edwin A.; Cleeves, L. Ilsedore; Brinch, Christian; Blake, Geoffrey A.; Lis, Dariusz C.; Melnick, Gary J.; Panić, Olja; Pearson, John C.; Kristensen, Lars; Yıldız, Umut A.; van Dishoeck, Ewine F.

    2016-06-01

    Context. Nitrogen chemistry in protoplanetary disks and the freeze-out on dust particles is key for understanding the formation of nitrogen-bearing species in early solar system analogs. In dense cores, 10% to 20% of the nitrogen reservoir is locked up in ices such as NH3, NH4+ and OCN-. So far, ammonia has not been detected beyond the snowline in protoplanetary disks. Aims: We aim to find gas-phase ammonia in a protoplanetary disk and characterize its abundance with respect to water vapor. Methods: Using HIFI on the Herschel Space Observatory, we detected for the first time the ground-state rotational emission of ortho-NH3 in a protoplanetary disk around TW Hya. We used detailed models of the disk's physical structure and the chemistry of ammonia and water to infer the amounts of gas-phase molecules of these species. We explored two radial distributions (extended across the disk and confined to <60 au like the millimeter-sized grains) and two vertical distributions (near the midplane and at intermediate heights above the midplane, where water is expected to photodesorb off icy grains) to describe the (unknown) location of the molecules. These distributions capture the effects of radial drift and vertical settling of ice-covered grains. Results: The NH310-00 line is detected simultaneously with H2O 110-101 at an antenna temperature of 15.3 mK in the Herschel beam; the same spectrum also contains the N2H+ 6-5 line with a strength of 18.1 mK. We use physical-chemical models to reproduce the fluxes and assume that water and ammonia are cospatial. We infer ammonia gas-phase masses of 0.7-11.0 × 1021 g, depending on the adopted spatial distribution, in line with previous literature estimates. For water, we infer gas-phase masses of 0.2-16.0 × 1022 g, improving upon earlier literature estimates This corresponds to NH3/H2O abundance ratios of 7%-84%, assuming that water and ammonia are co-located. The inferred N2H+ gas mass of 4.9 × 1021 g agrees well with earlier

  13. Optimizing the separation performance of a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Wood, H. G.

    1997-11-01

    Gas centrifuges were originally developed for the enrichment of U^235 from naturally occurring uranium for the purpose of providing fuel for nuclear power reactors and material for nuclear weapons. This required the separation of a binary mixture composed of U^235 and U^238. Since the end of the cold war, a surplus of enriched uranium exists on the world market, but many centrifuge plants exist in numerous countries. These circumstances together with the growing demand for stable isotopes for chemical and physical research and in medical science has led to the exploration of alternate applications of gas centrifuge technology. In order to acieve these multi-component separations, existing centrifuges must be modified or new centrifuges must be designed. In either case, it is important to have models of the internal flow fields to predict the separation performance and algorithms to seek the optimal operating conditions of the centrifuges. Here, we use the Onsager pancake model of the internal flow field, and we present an optimization strategy which exploits a similarity parameter in the pancake model. Numerical examples will be presented.

  14. Diameter control of gold nanoparticles synthesized in gas phase using atmospheric-pressure H2/Ar plasma jet and gold wire as the nanoparticle source: Control by varying the H2/Ar mixture ratio

    NASA Astrophysics Data System (ADS)

    Shimizu, Yoshiki

    2017-01-01

    This report describes diameter control of gold nanoparticles (AuNPs) during synthesis using an atmospheric-pressure H2/Ar plasma jet drive with pulse-modulated ultrahigh frequency, employing Au wire as the NP source material. During this process, where most of the AuNPs are regarded as formed through condensation from Au vapor derived by the Au wire etching, the mean diameter varied in the approximate range of 2-12 nm with H2 volume ratios up to 3.9%. In plasma diagnostics, results showed that the H2 volume ratio influences the plasma discharge behaviour, which affects the heat flux density flowed into the Au wire, and the atomic hydrogen concentration in the plasma. Both seemed to influence the etching rate of the Au wire per unit area, which is directly related to the concentration of Au vapor in the plasma. The concentration is one factor affecting the particle size evolution because of the collisions among vapor species in reaction field. Therefore, the AuNP size variation with the H2 volume ratio was discussed from the perspective of the etching rate of the Au wire at each H2 volume ratio.

  15. Investigation of cross-linked and additive containing polymer materials for membranes with improved performance in pervaporation and gas separation.

    PubMed

    Hunger, Katharina; Schmeling, Nadine; Jeazet, Harold B Tanh; Janiak, Christoph; Staudt, Claudia; Kleinermanns, Karl

    2012-10-22

    Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes.

  16. Investigation of Cross-Linked and Additive Containing Polymer Materials for Membranes with Improved Performance in Pervaporation and Gas Separation

    PubMed Central

    Hunger, Katharina; Schmeling, Nadine; Jeazet, Harold B. Tanh; Janiak, Christoph; Staudt, Claudia; Kleinermanns, Karl

    2012-01-01

    Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes. PMID:24958427

  17. 3,3',5,5'-tetramethylbenzidine/H2O2 staining is not specific for heme proteins separated by gel electrophoresis.

    PubMed

    Miller, D J; Nicholas, D J

    1984-08-01

    Staining of sodium dodecyl sulfate or lithium dodecyl sulfate gels with 3,3',5,5'-tetramethylbenzidine (TMBZ)/H2O2 after electrophoresis has frequently been used as a specific method of detecting heme proteins. That TMBZ is an electron donor for O2 reduction by the nonheme-soluble cytochrome oxidase/nitrite reductase from Nitrosomonas europaea is now shown; this protein is detected by the TMBZ/H2O2 method. A method for the determination of TMBZ oxidase activity is given; hence, the detection of artifactual staining due to proteins of this type is possible.

  18. Separation of SF6 from gas mixtures using gas hydrate formation.

    PubMed

    Cha, Inuk; Lee, Seungmin; Lee, Ju Dong; Lee, Gang-woo; Seo, Yongwon

    2010-08-15

    This study aims to examine the thermodynamic feasibility of separating sulfur hexafluoride (SF(6)), which is widely used in various industrial fields and is one of the most potent greenhouse gases, from gas mixtures using gas hydrate formation. The key process variables of hydrate phase equilibria, pressure-composition diagram, formation kinetics, and structure identification of the mixed gas hydrates, were closely investigated to verify the overall concept of this hydrate-based SF(6) separation process. The three-phase equilibria of hydrate (H), liquid water (L(W)), and vapor (V) for the binary SF(6) + water mixture and for the ternary N(2) + SF(6) + water mixtures with various SF(6) vapor compositions (10, 30, 50, and 70%) were experimentally measured to determine the stability regions and formation conditions of pure and mixed hydrates. The pressure-composition diagram at two different temperatures of 276.15 and 281.15 K was obtained to investigate the actual SF(6) separation efficiency. The vapor phase composition change was monitored during gas hydrate formation to confirm the formation pattern and time needed to reach a state of equilibrium. Furthermore, the structure of the mixed N(2) + SF(6) hydrate was confirmed to be structure II via Raman spectroscopy. Through close examination of the overall experimental results, it was clearly verified that highly concentrated SF(6) can be separated from gas mixtures at mild temperatures and low pressure conditions.

  19. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Liang Hu

    2006-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer (transportation layer phase) is used for the increase of absorption rate. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the liquid mass transfer

  20. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Tim Fout

    2007-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer is used for the increase of absorption rate, and plays the role of transportation of CO{sub 2}. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the

  1. Synthesis, pervaporation and gas separation studies of polyaniline blends

    SciTech Connect

    Huang, S.C.; Conklin, J.A.; Su, T.M.

    1995-12-01

    Membranes have been successfully produced from blends of polyaniline/polyacrylic acid and polyaniline/polyimide. The uniqueness of these membranes is the incorporation of {open_quotes}polymer dopants{close_quotes} in polyaniline. Conductivity measurements show that polyacrylic acid dopes the polyaniline. Pervaporation of water and water/acetic acid mixtures were performed using polyaniline and its polyacrylic acid blend. An improved flux over the polyaniline base form is observed. Polyaniline/polyimide blends were synthesized for gas permeability studies. These blends combine improved thermal stability relative to polyaniline with greater gas selectivity relative to polyimide. The blend shows an increase in permeability for all gases studied over both, polyaniline base and polyimide, while maintaining comparable separation factors.

  2. Counter pumping debris excluder and separator. [gas turbine shaft seals

    NASA Technical Reports Server (NTRS)

    Ludwig, L. P. (Inventor)

    1978-01-01

    A dirt separator and excluder for removing entrained debris from gas turbine shaft seals is described. A helical groove pattern is constructed on the rotating shaft with the pumping pattern such that it tends to pump seal pressurizing gas toward the gas turbine seal. A second helical groove pattern is provided on the stationary housing or counter rotating member coaxial with the shaft, and this pattern is designed to provide pumping in the direction opposite from that of the groove pattern on the shaft. Gas with entrained debris entering this grooved area will be subjected to high centrifugal forces due to the swirl motion induced by the groove pattern and the rotation of the shaft. This debris is centrifuged outwardly into the outer groove pattern on the housing or counter rotating member. Because the outer groove pattern has a pumping direction opposite from that of the seal, dirt is pumped away from the seal and can be collected in a suitable debris trap remote from the seal location.

  3. Selectivity trend of gas separation through nanoporous graphene

    SciTech Connect

    Liu, Hongjun; Chen, Zhongfang; Dai, Sheng; Jiang, De-en

    2014-01-29

    We demonstrate that porous graphene can efficiently separate gases according to their molecular sizes using molecular dynamic (MD) simulations,. The flux sequence from the classical MD simulation is H2>CO2>>N2>Ar>CH4, which generally follows the trend in the kinetic diameters. Moreover, this trend is also confirmed from the fluxes based on the computed free energy barriers for gas permeation using the umbrella sampling method and kinetic theory of gases. Both brute-force MD simulations and free-energy calcualtions lead to the flux trend consistent with experiments. Case studies of two compositions of CO2/N2 mixtures further demonstrate the separation capability of nanoporous graphene.

  4. Synthesis and Transport Properties of Novel MOF/PIM-1/MOF Sandwich Membranes for Gas Separation

    PubMed Central

    Fuoco, Alessio; Khdhayyer, Muhanned R.; Attfield, Martin P.; Esposito, Elisa; Jansen, Johannes C.; Budd, Peter M.

    2017-01-01

    Metal-organic frameworks (MOFs) were supported on polymer membrane substrates for the fabrication of composite polymer membranes based on unmodified and modified polymer of intrinsic microporosity (PIM-1). Layers of two different MOFs, zeolitic imidazolate framework-8 (ZIF-8) and Copper benzene tricarboxylate ((HKUST-1), were grown onto neat PIM-1, amide surface-modified PIM-1 and hexamethylenediamine (HMDA) -modified PIM-1. The surface-grown crystalline MOFs were characterized by a combination of several techniques, including powder X-ray diffraction, infrared spectroscopy and scanning electron microscopy to investigate the film morphology on the neat and modified PIM-1 membranes. The pure gas permeabilities of He, H2, O2, N2, CH4, CO2 were studied to understand the effect of the surface modification on the basic transport properties and evaluate the potential use of these membranes for industrially relevant gas separations. The pure gas transport was discussed in terms of permeability and selectivity, highlighting the effect of the MOF growth on the diffusion coefficients of the gas in the new composite polymer membranes. The results confirm that the growth of MOFs on polymer membranes can enhance the selectivity of the appropriately functionalized PIM-1, without a dramatic decrease of the permeability. PMID:28208658

  5. Computing at the Dubna gas-filled recoil separator

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yuri S.; Polyakov, Alexandr N.

    2006-03-01

    Simulation codes for the spectra of heavy implanted nuclei, applications for online data visualization and real time PC-based algorithms are considered. Special attention is paid to the application of real time techniques for radical suppression of background products in heavy-ion-induced nuclear reactions at the U-400 cyclotron of the Flerov Laboratory of Nuclear Reactions. The detection system of the Dubna gas-filled recoil separator (DGFRS) is also briefly described. Calculated heavy recoil spectra are compared with those measured in heavy-ion-induced nuclear reactions.

  6. Adsorption and Gas Separation of Molecules by Carbon Nanohorns.

    PubMed

    Gatica, Silvina M; Nekhai, Anton; Scrivener, Adam

    2016-05-19

    In this paper, we report the results of Monte Carlo simulations of the adsorption of neon, argon, methane and carbon dioxide in carbon nanohorns. We model the nanohorns as an array of carbon cones and obtained adsorption isotherms and isosteric heats. The main sites of adsorption are inside the cones and in the interstices between three cones. We also calculated the selectivity of carbon dioxide/methane, finding that nanohorns are a suitable substrate for gas separation. Our simulations are compared to available experimental data.

  7. Gas separation by composite solvent-swollen membranes

    DOEpatents

    Matson, S.L.; Lee, E.K.L.; Friesen, D.T.; Kelly, D.J.

    1989-04-25

    There is disclosed a composite immobilized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorus or sulfur atom, and having a boiling point of at least 100 C and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation. 3 figs.

  8. Gas separation by composite solvent-swollen membranes

    DOEpatents

    Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

    1989-01-01

    There is disclosed a composite immobulized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorous or sulfur atom, and having a boiling point of at least 100.degree. C. and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation.

  9. Methods of calculating engineering parameters for gas separations

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.

    1980-01-01

    A group additivity method has been generated which makes it possible to estimate, from the structural formulas alone, the energy of vaporization and the molar volume at 25 C of many nonpolar organic liquids. From these two parameters and appropriate thermodynamic relationships it is then possible to predict the vapor pressure of the liquid phase and the solubility of various gases in nonpolar organic liquids. The data are then used to evaluate organic and some inorganic liquids for use in gas separation stages or as heat exchange fluids in prospective thermochemical cycles for hydrogen production.

  10. Simulation and Fabrication of SAW-Based Gas Sensor with Modified Surface State of Active Layer and Electrode Orientation for Enhanced H2 Gas Sensing

    NASA Astrophysics Data System (ADS)

    Hasan, Md. Nazibul; Maity, Santanu; Sarkar, Argha; Bhunia, Chandan Tilak; Acharjee, Debabrata; Joseph, Aneesh M.

    2017-02-01

    The design, analysis, optimization, and fabrication of layered and nanostructure-based surface acoustic wave (SAW) gas sensors are presented. A lithium niobate and zinc oxide (ZnO) nano multilayer structure is proposed to enhance the sensitivity of the SAW-based gas sensor. Different materials are considered for the intermediate layer in the design for optimization purposes. The sensitivity of the sensor could be improved due to increased active surface area obtained by varying the aspect ratio of the nanorods, the thickness of the intermediate layer, and the gap between the electrodes. The total displacement and frequency shift of the device were significantly improved. Overall, the mechanically engineered surface-based (nanorod) SAW gas sensor offered better sensing response than the layered SAW gas sensor in terms of sensitivity performance.

  11. Gas cell based on optical contacting for fundamental spectroscopy studies with initial reference absorption spectrum of H2O vapor at 1723 K and 0.0235 bar

    NASA Astrophysics Data System (ADS)

    Melin, Scott T.; Sanders, Scott T.

    2016-09-01

    A gas cell, using optically contacted sapphire windows to form a hot vapor seal, has been created for high temperature fundamental spectroscopy studies. It is designed to operate at temperatures from 280-2273 K and pressures from vacuum to 1.3 bar. Using the cell in conjunction with an external cavity diode laser spectrometer, a reference H2O vapor absorption spectrum at P=0.0235±0.0036 bar and T=1723±6 K was measured with 0.0001 cm-1 resolution over the 7326-7598 cm-1 range. Comparison of the measured spectrum to simulations reveals errors in both the HITEMP and BT2 databases. This work establishes heated static cell capabilities at temperatures well above the typical limit of approximately 1300 K set by quartz material properties. This paper addresses the design of the cell as well as the cell's limitations.

  12. Membrane processes for gas separations: Part I. Removal of carbon dioxide and hydrogen sulfide from low-quality natural gas. Part II. Enrichment of krypton in air

    NASA Astrophysics Data System (ADS)

    Hao, Jibin

    1998-12-01

    I. The objective of this study was to determine the process design characteristics and economics of membrane separation processes for reducing the concentrations of H2S and CO2 in low-quality natural gas containing substantial amounts of the two acid gases to pipeline specifications ( ≤ 2 mole-% CO2 and ≤ 4 ppm H2S). The new processes considered the simultaneous use of two different types of polymer membranes for the above application, namely, one with higher CO2/CH4 selectivity and the other with higher H2S/CH4 selectivity. The performance and economics of membrane process configurations comprising one, two, and three permeation stages, with and without recycle streams, were examined and optimized via extensive computer simulations. Most computations assumed as a "base-case", the processing of a medium-size natural gas stream of 35 MMSCFD at 800 psia. The natural gas was taken to contain ≤ 10 mole-% H2S and ≤ 40 mole-% CO2. The most economical process configuration was two permeation stages in series, with H2S-selective membranes in the first stage and CO2-selective membranes in the second stage. The most economical process configurations for upgrading natural gas containing either only substantial amounts of H2S or of CO2 were also determined. The sensitivity of the process economics to feed flow rate, feed pressure, membrane module cost, and wellhead cost of natural gas was studied. A comparison of the processing cost of membrane processes with that of conventional gas absorption processes utilizing diethanolamine as solvent was also investigated. II. A membrane process for enrichment of Kr in air was studied experimentally as a technique of improving the accuracy of Kr analysis. "Asymmetric" silicone rubber membranes were found to be most suitable for this application. The study was investigated with a feed gas mixture containing 0.99 mole-% Kr, 20.70 mole-% O2, and 78.30 mole-% N2. The Kr concentration could be increased from 0.99 to 2.23 mole-% in a

  13. Stationary afterglow measurements of the temperature dependence of the electron–ion recombination rate coefficients of {{\\rm{H}}}_{2}{{\\rm{D}}}^{+} and {{HD}}_{2}^{+} in He/Ar/H2/D2 gas mixtures at T = 80–145 K 

    NASA Astrophysics Data System (ADS)

    Plašil, Radek; Dohnal, Petr; Kálosi, Ábel; Roučka, Štěpán; Johnsen, Rainer; Glosík, Juraj

    2017-03-01

    We report measurements of the binary and ternary recombination rate coefficients of deuterated isotopologues of {{{H}}}3+. A cavity ring-down absorption spectrometer was used to monitor the fractional abundances of {{{H}}}3+, {{{H}}}2{{{D}}}+, {{HD}}2+ and {{{D}}}3+ during the decay of a plasma in He/Ar/{{{H}}}2/{{{D}}}2 mixtures. A dependence of the measured effective recombination rate coefficients on the helium buffer gas density was observed and hence both the binary and the ternary recombination rate coefficients for {{{H}}}2{{{D}}}+ and {{HD}}2+ were obtained in the temperature range 80–145 K.

  14. The Yale Gas-Filled Split Pole Magnetic Separator

    NASA Astrophysics Data System (ADS)

    Cata-Danil, G.; Beausang, C. W.; Casten, R. F.; Chen, A.; Chubrich, N.; Cooper, J. R.; Krücken, R.; Liu, B.; Novak, J. R.; Visser, D.; Zamfir, N. V.

    1998-10-01

    Design and construction of a gas-filled recoil separator is underway at the Wright Nuclear Structure Laboratory at Yale University. By filling the magnetic field region of the existing Enge Split-Pole magnet with N2 or He2 gases in the 1 to 15 mbar pressure range a gradual focussing of discrete charge states has been measured. The incident ions were ^16O and ^35,37Cl with 49 MeV and 95 MeV energies, respectively. The process is understood as a result of coalescing of trajectories of different charge states around a trajectory defined by the mean charge state (q¯) of the ion in gas. Because q¯ depends on the atomic number Z and is roughly proportional with the ion velocity, the average magnetic rigidity (B¯ρ=Av/q¯) is almost independent of the velocity distribution of the incident ions. The ion trajectories will be therefore be mainly determined by the mass number A and the atomic number Z of the ion. Monte Carlo simulations with the code RAYTRACE closely reproduce the experimental behavior. We plan to use the Yale Mass Separator (YaMS) for nuclear structure studies in conjunction with high efficency gamma detectors (clover detectors) for enhancing weak reaction channels and fission background reduction. Work supported by the US-DOE under contract numbers DE-FG02-91ER-40609 and DE-FG02-88ER-40417.

  15. H2 blockers

    MedlinePlus

    ... ulcer disease - H2 blockers; PUD - H2 blockers; Gastroesophageal reflux - H2 blockers ... blockers are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This is a ...

  16. Measurements of hydrogen sulfide (H2S) using PTR-MS: calibration, humidity dependence, inter-comparison and results from field studies in an oil and gas production region

    NASA Astrophysics Data System (ADS)

    Li, R.; Warneke, C.; Graus, M.; Field, R.; Geiger, F.; Veres, P. R.; Soltis, J.; Li, S.-M.; Murphy, S. M.; Sweeney, C.; Pétron, G.; Roberts, J. M.; de Gouw, J.

    2014-06-01

    Natural gas production is associated with emissions of several trace gases, some of them classified as air toxics. While volatile organic compounds (VOCs) have received much attention, hydrogen sulfide (H2S) can also be of concern due to the known health impacts of exposure to this hazardous air pollutant. Here, we present quantitative, fast time-response measurements of H2S using Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) instruments. An Ultra-Light-Weight PTR-MS (ULW-PTR-MS) in a mobile laboratory was operated for measurements of VOCs and H2S in a gas and oil field during the Uintah Basin Winter Ozone Study (UBWOS) 2012 campaign. Measurements of VOCs and H2S by a PTR-MS were also made at the Horse Pool ground site in the Uintah Basin during UBWOS 2013. The H2S measurement by PTR-MS is strongly humidity dependent because the proton affinity of H2S is only slightly higher than that of water. The H2S sensitivity of PTR-MS ranged between 0.6-1.4 ncps ppbv-1 (normalized counts per second/parts per billion by volume) during UBWOS 2013. We compare the humidity dependence determined in the laboratory with in-field calibrations and determine the H2S mixing ratios for the mobile and ground measurements. The PTR-MS measurements at Horse Pool are evaluated by comparison with simultaneous H2S measurements using a PTR Time-of-Flight MS (PTR-ToF-MS) and a Picarro cavity ring down spectroscopy (CRDS) instrument for H2S/CH4. On average 0.6 ± 0.3 ppbv H2S was present at Horse Pool during UBWOS 2013. The correlation between H2S and methane enhancements suggests that the source of H2S is associated with oil and gas extraction in the basin. Significant H2S mixing ratios of up to 9 ppmv downwind of storage tanks were observed during the mobile measurements. This study suggests that H2S emissions associated with oil and gas production can lead to short-term high levels close to point sources, and elevated background levels away from those sources. In addition, our work has

  17. Measurements of hydrogen sulfide (H2S) using PTR-MS: calibration, humidity dependence, inter-comparison and results from field studies in an oil and gas production region

    NASA Astrophysics Data System (ADS)

    Li, R.; Warneke, C.; Graus, M.; Field, R.; Geiger, F.; Veres, P. R.; Soltis, J.; Li, S.-M.; Murphy, S. M.; Sweeney, C.; Pétron, G.; Roberts, J. M.; de Gouw, J.

    2014-10-01

    Natural gas production is associated with emissions of several trace gases, some of them classified as air toxics. While volatile organic compounds (VOCs) have received much attention, hydrogen sulfide (H2S) can also be of concern due to the known health impacts of exposure to this hazardous air pollutant. Here, we present quantitative, fast time-response measurements of H2S using proton-transfer-reaction mass-spectrometry (PTR-MS) instruments. An ultra-light-weight PTR-MS (ULW-PTR-MS) in a mobile laboratory was operated for measurements of VOCs and H2S in a gas and oil field during the Uintah Basin Winter Ozone Study (UBWOS) 2012 campaign. Measurements of VOCs and H2S by a PTR-MS were also made at the Horse Pool ground site in the Uintah Basin during UBWOS 2013. The H2S measurement by PTR-MS is strongly humidity dependent because the proton affinity of H2S is only slightly higher than that of water. The H2S sensitivity of PTR-MS ranged between 0.6-1.4 ncps ppbv-1 during UBWOS 2013. We compare the humidity dependence determined in the laboratory with in-field calibrations and determine the H2S mixing ratios for the mobile and ground measurements. The PTR-MS measurements at Horse Pool are evaluated by comparison with simultaneous H2S measurements using a PTR time-of-flight MS (PTR-ToF-MS) and a Picarro cavity ring down spectroscopy (CRDS) instrument for H2S / CH4. On average 0.6 ± 0.3 ppbv H2S was present at Horse Pool during UBWOS 2013. The correlation between H2S and methane enhancements suggests that the source of H2S is associated with oil and gas extraction in the basin. Significant H2S mixing ratios of up to 9 ppmv downwind of storage tanks were observed during the mobile measurements. This study suggests that H2S emissions associated with oil and gas production can lead to short-term high levels close to point sources, and elevated background levels away from those sources. In addition, our work has demonstrated that PTR-MS can make reliable measurements of

  18. Tuning of the internal energy and isomer distribution in small protonated water clusters H(+)(H2O)(4-8): an application of the inert gas messenger technique.

    PubMed

    Mizuse, Kenta; Fujii, Asuka

    2012-05-24

    Infrared spectroscopy of gas-phase hydrated clusters provides us much information on structures and dynamics of water networks. However, interpretation of spectra is often difficult because of high internal energy (vibrational temperature) of clusters and coexistence of many isomers. Here we report an approach to vary these factors by using the inert gas (so-called "messenger")-mediated cooling technique. Protonated water clusters with a messenger (M), H(+)(H(2)O)(4-8)·M (M = Ne, Ar, (H(2))(2)), are formed in a molecular beam and probed with infrared photodissociation spectroscopy in the OH stretch region. Observed spectra are compared with each other and with bare H(+)(H(2)O)(n). They show clear messenger dependence in their bandwidths and relative band intensities, reflecting different internal energy and isomer distribution, respectively. It is shown that the internal energy follows the order H(+)(H(2)O)(n) > H(+)(H(2)O)(n)·(H(2))(2) > H(+)(H(2)O)(n)·Ar > H(+)(H(2)O)(n)·Ne, while the isomer-selectivity, which changes the isomer distribution in the bare system, follows the order H(+)(H(2)O)(n)·Ar > H(+)(H(2)O)(n)·(H(2))(2) > H(+)(H(2)O)(n)·Ne ~ (H(+)(H(2)O)(n)). Although the origin of the isomer-selectivity is unclear, comparison among spectra measured with different messengers is very powerful in spectral analyses and makes it possible to easily assign spectral features of each isomer.

  19. Improvement of H2S Sensing Properties of SnO2-Based Thick Film Gas Sensors Promoted with MoO3 and NiO

    PubMed Central

    Lee, Soo Chool; Kim, Seong Yeol; Hwang, Byung Wook; Jung, Suk Yong; Ragupathy, Dhanusuraman; Son, In Sung; Lee, Duk Dong; Kim, Jae Chang

    2013-01-01

    The effects of the SnO2 pore size and metal oxide promoters on the sensing properties of SnO2-based thick film gas sensors were investigated to improve the detection of very low H2S concentrations (<1 ppm). SnO2 sensors and SnO2-based thick-film gas sensors promoted with NiO, ZnO, MoO3, CuO or Fe2O3 were prepared, and their sensing properties were examined in a flow system. The SnO2 materials were prepared by calcining SnO2 at 600, 800, 1,000 and 1,200 °C to give materials identified as SnO2(600), SnO2(800), SnO2(1000), and SnO2(1200), respectively. The Sn(12)Mo5Ni3 sensor, which was prepared by physically mixing 5 wt% MoO3 (Mo5), 3 wt% NiO (Ni3) and SnO2(1200) with a large pore size of 312 nm, exhibited a high sensor response of approximately 75% for the detection of 1 ppm H2S at 350 °C with excellent recovery properties. Unlike the SnO2 sensors, its response was maintained during multiple cycles without deactivation. This was attributed to the promoter effect of MoO3. In particular, the Sn(12)Mo5Ni3 sensor developed in this study showed twice the response of the Sn(6)Mo5Ni3 sensor, which was prepared by SnO2(600) with the smaller pore size than SnO2(1200). The excellent sensor response and recovery properties of Sn(12)Mo5Ni3 are believed to be due to the combined promoter effects of MoO3 and NiO and the diffusion effect of H2S as a result of the large pore size of SnO2. PMID:23519347

  20. Hybrid double hydrocyclone-gravity gas/liquid separator

    SciTech Connect

    Suh, S.L.; Reeds, C.B.; Van Scherpe, P.; Silcox, W.H.

    1986-10-14

    An apparatus is described for separation of a gas from a liquid in a multiphasic mixture, comprising: an enclosing chamber having a generally cylindrical shape, and an axis through its center; an outlet for allowing gas to leave the enclosing chamber; an outlet for allowing liquid to leave the enclosing chamber; means to control the liquid outflow; a generally smaller chamber within the enclosing chamber, constructed so that a space may be formed between both chambers; the smaller chamber having an inner surface the shape of two cones which are joined at their bases, an inflow line for pressurized well production fluid, the inflow line having an outlet located on the involute inner surface of the smaller chamber where the bases of the cones are joined; a blade means for splitting the flow of production fluid into a stream for each conical section, the blade means being located at the inflow outlet; two liquid outlets for the smaller chamber, the outlets being located at the point of each cone and directed downwards to the bottom of the enclosing chamber; and a gas outlet for the smaller chamber.

  1. Enantiomeric phase separation in a lattice gas model: Guggenheim approximation

    NASA Astrophysics Data System (ADS)

    Huckaby, Dale A.; Shinmi, Masato; Ausloos, Marcel; Clippe, Paulette

    1986-05-01

    We consider a lattice gas in which the two enantiomeric forms of a tetrahedral molecule, consisting of a central carbon atom bonded to four different groups A, B, G, and H, are adsorbed onto a triangular lattice, such that the carbon atom is above a lattice site, the three bonds to A, B, and G point toward neighboring lattice sites, and the bond to H points perpendicular to and away from the plane of the lattice. For a certain choice of intermolecular interactions, such as may exist between the zwitterion forms of an amino acid, the phase diagram was investigated using a Guggenheim approximation with two order parameters. Enantiomeric phase separation into two symmetric condensed phases occurs at low temperatures. These condensed phases become a single racemic condensed phase at a critical line, and they are in equilibrium with a racemic gas phase along a line of triple points. These two lines coincide at a critical endpoint. The racemic condensed and gas phases are in equilibrium along a two phase coexistence line which begins at the critical endpoint and ends at a critical point. No tricritical point was found in the model for the special choice of interactions studied.

  2. Memory and flexibility of cytokine gene expression as separable properties of human T(H)1 and T(H)2 lymphocytes.

    PubMed

    Messi, Mara; Giacchetto, Isabella; Nagata, Kinya; Lanzavecchia, Antonio; Natoli, Gioacchino; Sallusto, Federica

    2003-01-01

    CD4+ T cell priming under T helper type I (T(H)1) or T(H)2 conditions gives rise to polarized cytokine gene expression. We found that in these conditions human naive T cells acquired stable histone hyperacetylation at either the Ifng or Il4 promoter. Effector memory T cells showed polarized cytokine gene acetylation patterns in vivo, whereas central memory T cells had hypoacetylated cytokine genes but acquired polarized acetylation and expression after appropriate stimulation. However, hypoacetylation of the nonexpressed cytokine gene did not lead to irreversible silencing because most T(H)1 and T(H)2 cells acetylated and expressed the alternative gene when stimulated under opposite T(H) conditions. Such cytokine flexibility was absent in a subset of T(H)2 cells that failed to up-regulate T-bet and to express interferon-gamma when stimulated under T(H)1 conditions. Thus, most human CD4+ T cells retain both memory and flexibility of cytokine gene expression.

  3. Effects of sol-gel synthesis on 5Fe-15Mn-40Zn-40Ti-O mixed oxide structure and its H2S removal efficiency from industrial gas streams.

    PubMed

    Polychronopoulou, Kyriaki; Efstathiou, Angelos M

    2009-06-15

    A novel Fe-Mn-Zn-Ti-O mixed metal oxide has been developed for efficient low-temperature (25-50 degrees C) removal of H2S from a gas mixture containing 600 ppm H2S, 25 vol% H2, 7.5 vol % CO2, and 1-3 vol% H2O that simulates typical conditions experienced at the outlet of a bioreactor loaded with sulfate metal reducing bacteria (SMRB) that converts toxic Cr6+ and As5+ present in ground and surface waters and soils into nontoxic elements. During the latter conversion H2S gas is produced and has to be treated. In the present work it is demonstrated for the first time that by using the sol-gel synthesis route at given experimental conditions (e.g., metal precursor salts, solvent system, and solution pH), optimum structural properties for the Fe-Mn-Zn-Ti-O solid can be obtained for maximization of H2S uptake. In particular, at 25 degrees C an H2S uptake (0.085 g H2S/g solid) larger by at least a factor of 3 compared to a commercial Ni-based H2S absorbent material was obtained.

  4. Correlations of Polyimides and Blended Polyimides for High Temperature Gas Separations

    SciTech Connect

    John R. Klaehn; Christopher J. Orme; Thomas A. Luther; Eric S. Peterson; Jagoda M. Urban-Klaehn

    2002-03-01

    High performance polymers are of interest for high temperature gas separations, especially for the sequestration of carbon dioxide. A new family of high performance imide polymers has been identified as a successful membrane capture material. VTEC polyimides possess desired thermal properties (up to 500 °C) along with being robust and flexible even after multiple thermal cycles (up to 400 °C). Polyimides (PI) are excellent materials for high selectivity for smaller kinetic diameter gases such as H2 and CO2; however, they have low fluxes. We blended small amounts of different polymers with VTEC polyimide, which changes the fluxes. Another critical problem when working with glassy polymers is their moisture content. It has been found that water entrapped within the polymer matrix (left over from the solvent, or physisorbed) can also cause the polymer to change dramatically. Additionally presence of molecular water in the polymer’s void volume has been validated through Positron Annihilation Lifetime (PAL) spectroscopy. In this presentation, polymer characterization and gas-separation testing results will be discussed.

  5. Separation of Mercury from Flue Gas Desulfurization Scrubber Produced Gypsum

    SciTech Connect

    Hensman, Carl, E., P.h.D; Baker, Trevor

    2008-06-16

    Frontier Geosciences (Frontier; FGS) proposed for DOE Grant No. DE-FG02-07ER84669 that mercury control could be achieved in a wet scrubber by the addition of an amendment to the wet-FGD scrubber. To demonstrate this, a bench-scale scrubber and synthetic flue-gas supply was designed to simulate the limestone fed, wet-desulfurization units utilized by coal-fired power plants. Frontier maintains that the mercury released from these utilities can be controlled and reduced by modifying the existing equipment at installations where wet flue-gas desulfurization (FGD) systems are employed. A key element of the proposal was FGS-PWN, a liquid-based mercury chelating agent, which can be employed as the amendment for removal of all mercury species which enter the wet-FGD scrubber. However, the equipment design presented in the proposal was inadequate to demonstrate these functions and no significant progress was made to substantiate these claims. As a result, funding for a Phase II continuation of this work will not be pursued. The key to implementing the technology as described in the proposal and report appears to be a high liquid-to-gas ratio (L/G) between the flue-gas and the scrubber liquor, a requirement not currently implemented in existing wet-FGD designs. It may be that this constraint can be reduced through parametric studies, but that was not apparent in this work. Unfortunately, the bench-scale system constructed for this project did not function as intended and the funds and time requested were exhausted before the separation studies could occur.

  6. Effect of gas properties on the dynamics of the electrical slope asymmetry effect in capacitive plasmas: comparison of Ar, H2 and CF4

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Lafleur, T.; Gans, T.; O'Connell, D.; Greb, A.; Korolov, I.; Derzsi, A.; Donkó, Z.; Brandt, S.; Schüngel, E.; Schulze, J.; Diomede, P.; Economou, D. J.; Longo, S.; Johnson, E.; Booth, J.-P.

    2016-02-01

    Tailored voltage excitation waveforms provide an efficient control of the ion energy (through the electrical asymmetry effect) in capacitive plasmas by varying the ‘amplitude’ asymmetry of the waveform. In this work, the effect of a ‘slope’ asymmetry of the waveform is investigated by using sawtooth-like waveforms, through which the sheath dynamic can be manipulated. A remarkably different discharge dynamic is found for Ar, H2, and CF4 gases, which is explained by the different dominant electron heating mechanisms and plasma chemistries. In comparison to Argon we find that the electrical asymmetry can even be reversed by using an electronegative gas such as CF4. Phase resolved optical emission spectroscopy measurements, probing the spatiotemporal distribution of the excitation rate show excellent agreement with the results of particle-in-cell simulations, confirming the high degree of correlation between the excitation rates with the dominant heating mechanisms in the various gases. It is shown that, depending on the gas used, sawtooth-like voltage waveforms may cause a strong asymmetry.

  7. Advanced separation technology for flue gas cleanup. Topical report

    SciTech Connect

    Bhown, A.S.; Alvarado, D.; Pakala, N.; Ventura, S.

    1995-01-01

    The objective of this work is to develop a novel system for regenerable SO{sub 2} and NO{sub x} scrubbing of flue gas that focuses on (1) a novel method for regenerating spent SO{sub 2} scrubbing liquor and (2) novel chemistry for reversible absorption of NO{sub x}. In addition, high efficiency hollow fiber contactors (HFC) are proposed as the devices for scrubbing the SO{sub 2} and NO{sub x} from the flue gas. The system will be designed to remove more than 95% of the SO{sub 2} and more than 75% of the NO{sub x} from flue gases typical of pulverized coal-fired power plants at a cost that is at least 20% less than combined wet limestone scrubbing of SO{sub x} and selective catalytic reduction of NO{sub x}. The process will generate only marketable by-products. Our approach is to reduce the capital cost by using high-efficiency hollow fiber devices for absorbing and desorbing the SO{sub 2} and NO{sub x}. We will also introduce new process chemistry to minimize traditionally well-known problems with SO{sub 2} and NO{sub x} absorption and desorption. Our novel chemistry for scrubbing NO{sub x} will consist of water-soluble phthalocyanine compounds invented by SRI as well as polymeric forms of Fe{sup ++} complexes similar to traditional NO{sub x} scrubbing media. The final novelty of our approach is the arrangement of the absorbers in cassette (stackable) form so that the NO{sub x} absorber can be on top of the SO{sub x} absorber. This arrangement is possible only because of the high efficiency of the hollow fiber scrubbing devices, as indicated by our preliminary laboratory data. This arrangement makes it possible for the SO{sub 2} and NO{sub x} scrubbing chambers to be separate without incurring the large ducting and gas pressure drop costs necessary if a second conventional absorber vessel were used. Because we have separate scrubbers, we will have separate liquor loops and simplify the chemical complexity of simultaneous SO{sub 2}/NO{sub x} scrubbing.

  8. WATER-GAS SHIFT WITH INTEGRATED HYDROGEN SEPARATION PROCESS

    SciTech Connect

    Maria Flytzani-Stephanopoulos; Xiaomei Qi; Scott Kronewitter

    2004-02-01

    This project involved fundamental research and development of novel cerium oxide-based catalysts for the water-gas-shift reaction and the integration of these catalysts with Pd-alloy H{sub 2} -separation membranes supplying high purity hydrogen for fuel cell use. Conditions matching the requirements of coal gasifier-exit gas streams were examined in the project. Cu-cerium oxide was identified as the most promising high-temperature water-gas shift catalyst for integration with H{sub 2}-selective membranes. Formulations containing iron oxide were found to deactivate in the presence of CO{sub 2}. Cu-containing ceria catalysts, on the other hand, showed high stability in CO{sub 2}-rich gases. This type gas will be present over much of the catalyst, as the membrane removes the hydrogen produced from the shift reaction. The high-temperature shift catalyst composition was optimized by proper selection of dopant type and amount in ceria. The formulation 10at%Cu-Ce(30at%La)O{sub x} showed the best performance, and was selected for further kinetic studies. WGS reaction rates were measured in a simulated coal-gas mixture. The apparent activation energy, measured over aged catalysts, was equal to 70.2 kJ/mol. Reaction orders in CO, H{sub 2}O, CO{sub 2} and H{sub 2} were found to be 0.8, 0.2, -0.3, and -0.3, respectively. This shows that H{sub 2}O has very little effect on the reaction rate, and that both CO{sub 2} and H{sub 2} weakly inhibit the reaction. Good stability of catalyst performance was found in 40-hr long tests. A flat (38 cm{sup 2}) Pd-Cu alloy membrane reactor was used with the catalyst washcoated on oxidized aluminum screens close coupled with the membrane. To achieve higher loadings, catalyst granules were layered on the membrane itself to test the combined HTS activity/ H{sub 2} -separation efficiency of the composite. Simulated coal gas mixtures were used and the effect of membrane on the conversion of CO over the catalyst was evidenced at high space

  9. MELCOR-H2

    SciTech Connect

    2009-11-10

    Before this LDRD research, no single tool could simulate a very high temperature reactor (VHTR) that is coupled to a secondary system and the sulfur iodine (SI) thermochemistry. Furthermore, the SI chemistry could only be modeled in steady state, typically via flow sheets. Additionally, the MELCOR nuclear reactor analysis code was suitable only for the modeling of light water reactors, not gas-cooled reactors. We extended MELCOR in order to address the above deficiencies. In particular, we developed three VHTR input models, added generalized, modular secondary system components, developed reactor point kinetics, included transient thermochemistry for the most important cycles [SI and the Westinghouse hybrid sulfur], and developed an interactive graphical user interface for full plant visualization. The new tool is called MELCOR-H2, and it allows users to maximize hydrogen and electrical production, as well as enhance overall plant safety. We conducted validation and verification studies on the key models, and showed that the MELCOR-H2 results typically compared to within less than 5% from experimental data, code-to-code comparisons, and/or analytical solutions.

  10. Conduction mechanism and gas sensing properties of CoFe2O4 nanocomposite thick films for H2S gas.

    PubMed

    Bodade, Anjali B; Bodade, Archana B; Wankhade, H G; Chaudhari, G N; Kothari, D C

    2012-01-30

    Nanocrystalline 10 wt% Ni and 0.2 wt% Sm doped CoFe(2)O(4) was prepared by sol-gel citrate method and calcined at different temperatures. The CoFe(2)O(4) nanoparticles were characterized by X-ray diffraction (XRD), electrical properties were studied by impedance analysis. The XRD of CoFe(2)O(4) shows cubic structure with grain growth of 40 nm. The ac conductivity was studied for the sample 10 wt% Ni and 0.2 wt% Sm doped CoFe(2)O(4) calcined at 650°C, at temperature range from 100 to 700°C over a wide range of frequencies from 50 Hz to 200 kHz. The result indicates that the ac conductivity depend on temperature, frequency and concentration of dopant. Nanocrystalline 10 wt% Ni and 0.2 wt% Sm doped CoFe(2)O(4) was found to be good H(2)S sensor with high sensitivity and selectivity.

  11. An isotope separator for small noble gas samples

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Rauber, D. F.; Thonnard, N.; Willis, R. D.

    1987-11-01

    A Wien filter isotope enrichment system has been combined with a small turbomolecular pump to form a closed isotope separator for small noble gas samples. Atoms which leave the exit aperture of the plasma discharge ion source without being ionized are circulated back into the source through a feedback line. The system can be operated for several hours in a closed mode to collect up to 50% of the total number of atoms of a selected isotope (e.g. 81Kr) out of a small gas sample of only 2 × 10 -3 cm 3 STP. Ions are implanted at 10 kV into an aluminized Kapton foil after a flight distance of 150 cm. A beam stabilization system centers the ion beam in two perpendicular directions onto a target aperture to maintain a high enrichment factor of at least 10 3 over extended periods of time. Calibration of the enrichment process is achieved by isotope dilution. The system is a key part of the sample processing for 81Kr and 85Kr analysis by laser resonance ionization spectroscopy for applications in isotope geophysics.

  12. Separation of Flue-Gas Scrubber Sludge into Marketable Products

    SciTech Connect

    1998-02-28

    The reduction of sulfur oxides from high sulfur coal burning utility companies has resulted in the production of huge quantities of wet flue-gas desulfurization scrubber sludge. A typical 400 MW power station burning a coal containing 3.5% sulfur by weight and using a limestone absorbent would produce approximately 177,000 tons (dry weight) of scrubber sludge per year. This brownish colored, finely divided material contains calcium sulfite (CaSO{sub 3} {center_dot} 1/2 H{sub 2}O), calcium sulfate (CaSO{sub 4} {center_dot} 2H{sub 2}O), unreacted limestone (CaCO{sub 3}), and various other impurities such as fly-ash and iron oxide particles. The physical separation of the components of scrubber sludge would result in the re-use of this material. The primary use would be conversion to a highly pure synthetic gypsum. This technical report concentrates on the effect of baffle configuration on the separation of calcium sulfite/sulfate from limestone. The position of the baffles as they related to the feed inlet, and the quantity of the baffles were examined. A clean calcium sulfite/sulfate (less than 2.0% limestone by weight) was achieved with the combination of water-only cyclone and horizontally baffled column.

  13. Theoretical studies of UO2(H2O)n2+,NpO2(H2O)n+, and PuO2(H2O)n2+ complexes (n=4-6) in aqueous solution and gas phase

    NASA Astrophysics Data System (ADS)

    Cao, Zhiji; Balasubramanian, K.

    2005-09-01

    Extensive ab initio calculations both in gas phase and solution have been carried out to study the equilibrium structure, vibrational frequencies, and bonding characteristics of various actinyl (UO22+,NpO2+, and PuO22+) and their hydrated forms, AnO2(H2O)nz + (n =4, 5, and 6). Bulk solvent effects were studied using a continuum method. The geometries were fully optimized at the coupled-cluster singles + doubles (CCSD), density-functional theory (DFT), and Møller-Plesset (MP2) level of theories. In addition vibrational frequencies have been obtained at the CCSD as well as MP2/DFT levels. The results show that both the short-range and long-range solvent effects are important. The combined discrete-continuum model, in which the ionic solute and the solvent molecules in the first and second solvation shells are treated quantum mechanically while the solvent is simulated by a continuum model, can predict accurately the bonding characteristics. Moreover, our values of solvation free energies suggest that five- and six-coordinations are equally preferred for UO22+, and five-coordinated species are preferred for NpO2+ and PuO22+. On the basis of combined quantum-chemical and continuum treatments of the hydrated complexes, we are able to determine the optimal cavity radii for the solvation models. The coupled-cluster computations with large basis sets were employed for the vibrational spectra and equilibrium geometries both of which compare quite favorably with experiment. Our most accurate computations reveal that both five- and six-coordination complexes are important for these species.

  14. Morphology, structure, and properties of Cu-poor and Cu-rich Cu(In,Ga)Se2 films partially selenized using H2Se gas

    NASA Astrophysics Data System (ADS)

    Han, Anjun; Huang, Yongliang; Liu, Xiaohui; Xian, Wang; Meng, Fanying; Liu, Zhengxin

    2016-11-01

    Cu-poor and Cu-rich metallic precursors were prepared by cosputtering from In and Cu-Ga alloy targets and then partially selenized using H2Se gas. The properties of Cu(In,Ga)Se2 (CIGS) films are comparatively studied and the phase transition process is analyzed. The cosputtered metallic precursor has a rough morphology mostly covered by large In-rich nodules. After selenization, a large number of crumblike InSe grains were formed from the nodules on the surface of the Cu-rich film, whereas the Cu-poor film shows a dense surface. The selenized films comprise CIGS, Cu9(In,Ga)4 intermetallic, and the InSe phases. The proportion of the Cu9(In,Ga)4 phase in the Cu-rich film is more than that in the Cu-poor film. After annealing, the residual Cu9(In,Ga)4 of the Cu-poor film is eliminated. A negligible effect of Cu/(In+Ga) on the grain size can be observed. The CIGS solar cell with an efficiency of 15.1% was prepared by this method.

  15. Temperature dependent selective gas sorption of the microporous metal-imidazolate framework [Cu(L)] [H2L = 1,4-di(1H-imidazol-4-yl)benzene].

    PubMed

    Chen, Shui-Sheng; Chen, Min; Takamizawa, Satoshi; Chen, Man-Sheng; Su, Zhi; Sun, Wei-Yin

    2011-01-14

    A highly stable copper(II) microporous framework with cylindrical channels constructed from 1,4-di(1H-imidazol-4-yl)benzene (H(2)L) and CuCl(2)·2H(2)O is composed of Cu(II)-imidazolate tubes interconnected by the 1,4-phenylene group of L(2-), and shows temperature dependent selective gas sorption properties.

  16. Enhanced H2 separation through mixed proton-electron conducting membranes based on La5.5 W0.8 M0.2 O11.25-δ.

    PubMed

    Escolastico, Sonia; Seeger, Janka; Roitsch, Stefan; Ivanova, Mariya; Meulenberg, Wilhelm A; Serra, José M

    2013-08-01

    La(5.5) WO11.25-δ is a proton-conducting oxide that shows high protonic conductivity, sufficient electronic conductivity, and stability in moist CO2 environments. However, the H2 flows achieved to date when using La(5.5) WO11.25-δ membranes are still below the threshold for practical application in industrial processes. With the aim of improving the H2 flow obtained with this material, La(5.5) WO11.25-δ was doped in the W position by using Re and Mo; the chosen stoichiometry was La(5.5) W0.8 M0.2 O11.25-δ . This work presents the electrochemical characterization of these two compounds under reducing conditions, the H2 separation properties, as well as the influence of the H2 concentration in the feed stream, degree of humidification, and operating temperature. Doping with both Re and Mo enabled the magnitude of H2 permeation to be enhanced, reaching unrivaled values of up to 0.095 mL min(-1) cm(-2) at 700 °C for a La(5.5) W0.8 Re0.2 O11.25-δ membrane (760 μm thick). The spent membranes were investigated by using XRD, SEM, and TEM on focused-ion beam lamellas. Furthermore, the stability in CO2 -rich and H2 S-containing atmospheres was evaluated, and the compounds were shown to be stable in the atmospheres studied.

  17. Engineering the performance of mixed matrix membranes for gas separations

    NASA Astrophysics Data System (ADS)

    Shu, Shu

    Mixed matrix membranes that comprise domains of organic and inorganic components are investigated in this research. Such materials effectively circumvent the polymeric 'upper bound trade-off curve' and show properties highly attractive for industrial gas separations. Nevertheless, lack of intrinsic compatibility between the organic polymers and inorganic fillers poses the biggest challenge to successful fabrication of mixed matrix membranes. Consequently, control of the nanoscale interface between the sieve and polymer has been the key technical challenge to the implementation of composite membrane materials. The overarching goal of this research was to devise and explore approaches to enhance the performance of mixed matrix membranes by properly tailoring the sieve/polymer interface. In an effort to pursue the aforementioned objective, three approaches were developed and inspected: (i) use of silane coupling agents, (ii) hydrophobizing of sieve surface through alcohol etherification reactions, and (iii) a two-step modification sequence involving the use of a Grignard reagent. A comparison was drawn to evaluate these methodologies and the most effective strategy (Grignard treatment) was selected and further investigated. Successful formulation and characterization of mixed matrix membranes constituting zeolite 4A modified via the Grignard treatment are described in detail. Membranes with impressive improvements in gas separation efficiency and mechanical properties were demonstrated. The basis for the improvements in polymer/sieve compatibility enabled by this specific process were proposed and investigated. A key aspect of the present study was illuminating the detailed chemical mechanisms involved in the Grignard modification. Systematic characterization and carefully designed experiments revealed that the formation of distinctive surface structures is essentially a heterogeneous nucleation process, where Mg(OH)2 crystals grow from the nuclei previously extracted

  18. 3-D agricultural air quality modeling: Impacts of NH3/H2S gas-phase reactions and bi-directional exchange of NH3

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Zhang, Yang

    2014-12-01

    Accurately simulating the transport and fate of reduced nitrogen (NHx = ammonia (NH3) + ammonium (NH4+))- and sulfur-containing compounds emitted from agricultural activities represents a major challenge in agricultural air quality modeling. In this study, the Community Multiscale Air Quality (CMAQ) modeling system is further developed and improved by implementing 22 ammonia (NH3)/hydrogen sulfide (H2S) related gas-phase reactions and adjusting a few key parameters (e.g., emission potential) for bi-directional exchange of NH3 fluxes. Several simulations are conducted over the eastern U.S. domain at a 12-km horizontal resolution for January and July 2002 to examine the impacts of those improved treatments on air quality. The 5th generation mesoscale model (MM5) and CMAQ predict an overall satisfactory and consistent performance with previous modeling studies, especially for 2-m temperature, 2-m relative humidity, ozone (O3), and fine particulate matter (PM2.5). High model biases exist for precipitation in July and also dry/wet depositions. The updated model treatments contribute to O3, NHx, and PM2.5 by up to 0.4 ppb, 1.0 μg m-3, and 1.0 μg m-3 in January, respectively, and reduce O3 by up to 0.8 ppb and contribute to NHx and PM2.5 by up to 1.2 and 1.1 μg m-3 in July, respectively. The spatial distributions of O3 in both months and sulfur dioxide (SO2) in January are mainly affected by inline dry deposition velocity calculation. The spatial distributions of SO2 and sulfate (SO42-) in July are affected by both inline dry deposition velocity and NH3/H2S reactions. The variation trends of NH3, NHx, ammonium nitrate (NH4NO3), PM2.5 and total nitrogen (TN) are predominated by bi-directional exchange of NH3 fluxes. Uncertainties of NH3 emission potentials and empirical constants used in the bi-directional exchange scheme may significantly affect the concentrations of NHx and PM2.5, indicating that a more accurate and explicit treatment for those parameters should be

  19. Engineering design and theoretical analysis of nanoporous carbon membranes for gas separation

    NASA Astrophysics Data System (ADS)

    Acharya, Madhav

    1999-11-01

    Gases are used in a direct or indirect manner in virtually every major industry, such as steel manufacturing, oil production, foodstuffs and electronics. Membranes are being investigated as an alternative to established methods of gas separation such as pressure swing adsorption and cryogenic distillation. Membranes can be used in continuous operation and work very well at ambient conditions, thus representing a tremendous energy and economic saving over the other technologies. In addition, the integration of reaction and separation into a single unit known as a membrane reactor has the potential to revolutionize the chemical industry by making selective reactions a reality. Nanoporous carbons are highly disordered materials obtained from organic polymers or natural sources. They have the ability to separate gas molecules by several different mechanisms, and hence there is a growing effort to form them into membranes. In this study, nanoporous carbon membranes were prepared on macroporous stainless steel supports of both tubular and disk geometries. The precursor used was poly(furfuryl alcohol) and different synthesis protocols were employed. A spray coating method also was developed which allowed reproducible synthesis of membranes with very few defects. High gas selectivities were obtained such as O2/N2 = 6, H2/C2H 4 = 70 and CO2/N2 = 20. Membranes also were characterized using SEM and AFM, which revealed thin layers of carbon that were quite uniform and homogeneous. The simulation of nanoporous carbon structures also was carried out using a simple algorithmic approach. 5,6 and 7-membered rings were introduced into the structure, thus resulting in considerable curvature. The density of the structures were calculated and found to compare favorably with experimental findings. Finally, a theoretical analysis of size selective transport was performed using transition state theory concepts. A definite correlation of gas permeance with molecular size was obtained after

  20. Stable Cu2O nanocrystals grown on functionalized graphene sheets and room temperature H2S gas sensing with ultrahigh sensitivity

    NASA Astrophysics Data System (ADS)

    Zhou, Lisha; Shen, Fangping; Tian, Xike; Wang, Donghong; Zhang, Ting; Chen, Wei

    2013-01-01

    Stable Cu2O nanocrystals of around 3 nm were uniformly and densely grown on functionalized graphene sheets (FGS), which act as molecular templates instead of surfactants for controlled nucleation; the distribution density of nanocrystals can be easily controlled by FGS with different C/O ratios. The nanocomposite displays improved stability of the crystalline phase in wet air, which is attributed to finite-size effects that the high-symmetry crystalline phase is to be more stable at smaller size. Meanwhile, we conjecture that the oxygen adsorbed on the interfacial surface prefers to extract electrons from FGS, thus the interfacial bonding also makes a contribution in alleviating the process of corrosion to some extent. More importantly, the Cu2O-FGS nanocomposite based sensor realizes room temperature sensing to H2S with fantastic sensitivity (11%); even at the exposed concentration of 5 ppb, the relative resistance changes show good linearity with the logarithm of the concentration. The enhancement of sensitivity is attributed to the synergistic effect of Cu2O and FGS; on the one hand, surfactant-free capped Cu2O nanocrystals display higher surface activity to adsorb gas molecules, and on the other hand, FGS acting as conducting network presents greater electron transfer efficiency. These observations show that the Cu2O-FGS nanocomposite based sensors have potential applications for monitoring air pollution at room temperature with low cost and power consumption.Stable Cu2O nanocrystals of around 3 nm were uniformly and densely grown on functionalized graphene sheets (FGS), which act as molecular templates instead of surfactants for controlled nucleation; the distribution density of nanocrystals can be easily controlled by FGS with different C/O ratios. The nanocomposite displays improved stability of the crystalline phase in wet air, which is attributed to finite-size effects that the high-symmetry crystalline phase is to be more stable at smaller size. Meanwhile

  1. Extraction of Mg(OH)2 from Mg silicate minerals with NaOH assisted with H2O: implications for CO2 capture from exhaust flue gas.

    PubMed

    Madeddu, Silvia; Priestnall, Michael; Godoy, Erik; Kumar, R Vasant; Raymahasay, Sugat; Evans, Michael; Wang, Ruofan; Manenye, Seabelo; Kinoshita, Hajime

    2015-01-01

    The utilisation of Mg(OH)2 to capture exhaust CO2 has been hindered by the limited availability of brucite, the Mg(OH)2 mineral in natural deposits. Our previous study demonstrated that Mg(OH)2 can be obtained from dunite, an ultramafic rock composed of Mg silicate minerals, in highly concentrated NaOH aqueous systems. However, the large quantity of NaOH consumed was considered an obstacle for the implementation of the technology. In the present study, Mg(OH)2 was extracted from dunite reacted in solid systems with NaOH assisted with H2O. The consumption of NaOH was reduced by 97% with respect to the NaOH aqueous systems, maintaining a comparable yield of Mg(OH)2 extraction, i.e. 64.8-66%. The capture of CO2 from a CO2-N2 gas mixture was tested at ambient conditions using a Mg(OH)2 aqueous slurry. Mg(OH)2 almost fully dissolved and reacted with dissolved CO2 by forming Mg(HCO3)2 which remained in equilibrium storing the CO2 in the aqueous solution. The CO2 balance of the process was assessed from the emissions derived from the power consumption for NaOH production and Mg(OH)2 extraction together with the CO2 captured by Mg(OH)2 derived from dunite. The process resulted as carbon neutral when dunite is reacted at 250 °C for durations of 1 and 3 hours and CO2 is captured as Mg(HCO3)2.

  2. Gas separations using ceramic membranes. Final report, September 1988--February 1993

    SciTech Connect

    Lin, C.L.; Wu, J.C.S.; Gallaher, G.R.; Smith, G.W.; Flowers, D.L.; Gerdes, T.E.; Liu, P.K.T.

    1993-02-01

    This study covers a comprehensive evaluation of existing ceramic membranes for high temperature gas separations. Methodology has been established for microporous characterization stability and gas separation efficiency. A mathematical model was developed to predict gas separations with existing membranes. Silica and zeolitic modifications of existing membranes were pursued to enhance its separation efficiency. Some of which demonstrate unique separations properties. Use of the dense-silica membranes for hydrogen enrichment was identified as a promising candidate for future development. In addition, the decomposition of trace ammonia contaminant via a catalytic membrane reactor appears feasible. A further economic analysis is required to assess its commercial viability.

  3. Hydrophobic liquid/gas separator for heat pipes

    NASA Technical Reports Server (NTRS)

    Marcus, B. D.

    1972-01-01

    Perforated nonwetting plug of material such as polytetrafluoroethylene is mounted in gas reservoir feed tube, preferably at end which extends into heat pipe condenser section, to prevent liquid from entering gas reservoir of passively controlled heat pipe.

  4. Carbon-fiber composite molecular sieves for gas separation

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.

    1996-08-01

    This report describes continuing work on the activation and characterization of formed carbon fiber composites. The composites are produced at the Oak Ridge National Laboratory (ORNL) and activated at the Center for Applied Energy Research (CAER) using steam, CO{sub 2}, or O{sub 2} at different conditions of temperature and time, and with different furnace configurations. The general aims of the project are to produce uniformly activated samples with controlled pore structures for specialist applications such as gas separation and water treatment. In previous work the authors reported that composites produced from isotropic pitch fibers weighing up to 25g can be uniformly activated through the appropriate choice of reaction conditions and furnace configurations. They have now succeeded in uniformly activating composites of dimensions up to 12 x 7 x 6 cm, or up to about 166 gram - a scale-up factor of about six. Part of the work has involved the installation of a new furnace that can accommodate larger composites. Efforts were made to achieve uniform activation in both steam and CO{sub 2}. The authors have also succeeded in producing materials with very uniform and narrow pore size distributions by using a novel method involving low temperature oxygen chemisorption in combination with heat treatment in N{sub 2} at high temperatures. Work has also started on the activation of PAN based carbon fibers and fiber composites with the aim of producing composites with wide pore structures for use as catalyst supports. So far activation of the PAN fiber composites supplied by ORNL has been difficult which is attributed to the low reactivity of the PAN fibers. As a result, studies are now being made of the activation of the PAN fibers to investigate the optimum carbonization and activation conditions for PAN based fibers.

  5. Thermodynamic description of equilibria in mixed fluids (H 2O-non-polar gas) over a wide range of temperature (25-700°C) and pressure (1-5000 bars)

    NASA Astrophysics Data System (ADS)

    Akinfiev, Nikolai; Zotov, Alexander

    1999-07-01

    A new method for computing complicated equilibria in hydrothermal mixed fluids, H 2O-non-polar gas, is proposed. The computation algorithm is based on the electrostatic approach for the interaction between aqueous species and H 2O. The approach uses the SUPCRT92 database and the HKF format and may be considered as an application of the revised HKF model for mixed H 2O-non-polar gas fluids. Thermodynamic properties of dissolved gases at high temperatures and pressures are calculated using the Redlich-Kwong approach. Dielectric permittivity of the mixed solvent is estimated by the modified Kirkwood equation. The proposed approach is validated using available experimental data on the dissociation constants of H 2O and NaCl and the solubility of both covalent and ion crystals (SiO 2, AgCl, Ag 2SO 4, Ca(OH) 2, CaCO 3) in H 2O-non-polar component (dioxane, Ar, CO 2) mixtures. Predicted and experimental data are in close agreement over a wide range of P- T- xgas conditions (up to 500°C, 4 kbar and 0.25-0.3 mole fraction of non-polar gas). It is also shown how the computation method can be applied to estimate the Born parameters of aqueous species. The proposed approach enables not only examination of isolated reactions, but the study of equilibria of whole systems. Thus, it allows modelling of mixed natural fluids.

  6. Separations of hazardous organics from gas and liquid feedstreams using phosphazene polymer membranes

    SciTech Connect

    Peterson, E.S.; Stone, M.L.; Cummings, D.G.; McCaffrey, R.R.

    1993-01-01

    The liquid-liquid and gas separation properties for the separation of hazardous organic feed streams using pervaporation and gas separation methods with poly[bis(phenoxy)phosphazene] based membranes are reported. Liquid transport behavior was determined using pervaporation techniques. The preliminary gas separations were studied using a mixed gas separation method which the authors have described previously. Using the membrane pervaporation technique, separation factors of 10,000 have been routinely achieved for the separation of methylene chloride from water. Other tests have shown similar results for the removal of hydrocarbon vapors from air. Membranes were prepared using solution casting techniques. Solvent evaporation rates during the casting and subsequent curing processes were controlled to provide a consistent membrane microstructure. These results suggest that polyphosphazene membrane technology could effectively be used in cleaning up air and ground water that has been contaminated with chlorinated hydrocarbons.

  7. Sulfur Tolerant Pd/Cu and Pd/Au Alloy Membranes for H2 Separation with High Pressure CO2 for Sequestration

    SciTech Connect

    Yi Hua Ma; Natalie Pomerantz; Chao-Huang Chen

    2008-09-30

    The effect of H{sub 2}S poisoning on Pd, Pd/Cu, and Pd/Au alloy composite membranes prepared by the electroless deposition method on porous Inconel supports was investigated to provide a fundamental understanding of the durability and preparation of sulfur tolerant membranes. X-ray photoelectron spectroscopy (XPS) studies showed that the exposure of pure Pd to 50 ppm H{sub 2}S/H{sub 2} mixtures caused bulk sulfide formation at lower temperatures and surface sulfide formation at higher temperatures. Lower temperatures, longer exposure times, and higher H{sub 2}S concentrations resulted in a higher degree of sulfidation. In a Pd membrane, the bulk sulfide formation caused a drastic irrecoverable H{sub 2} permeance decline and an irreparable loss in selectivity. Pd/Cu and Pd/Au alloy membranes exhibited permeance declines due to surface sulfide formation upon exposure to 50 ppm H{sub 2}S/H{sub 2} gas mixtures. However in contrast to the pure Pd membrane, the permeances of the Pd/Cu and Pd/Au alloy membranes were mostly recovered in pure H{sub 2} and the selectivity of the Pd alloy layers remained essentially intact throughout the characterization in H{sub 2}, He and H{sub 2}S/H{sub 2} mixtures which lasted several thousand hours. The amount of irreversible sulfur poisoning decreased with increasing temperature due to the exothermicity of H{sub 2}S adsorption. Longer exposure times increased the amount of irreversible poisoning of the Pd/Cu membrane but not the Pd/Au membrane. Pd/Au coupon studies of the galvanic displacement method showed that higher Au{sup 3+} concentrations, lower pH values, higher bath temperatures and stirring the bath at a rate of 200 rpm yielded faster displacement rates, more uniform depositions, and a higher Au content within the layers. While 400 C was found to be sufficient to form a Pd/Au alloy on the surface, high temperature X-ray diffraction (HTXRD) studies showed that even after annealing between 500-600 C, the Pd/Cu alloys could have

  8. Gas Sensing of SnO2 Nanocrystals Revisited: Developing Ultra-Sensitive Sensors for Detecting the H2S Leakage of Biogas

    PubMed Central

    Mei, Lin; Chen, Yuejiao; Ma, Jianmin

    2014-01-01

    As a typical mode of energy from waste, biogas technology is of great interest to researchers. To detect the trace H2S released from biogas, we herein demonstrate a high-performance sensor based on highly H2S-sensitive SnO2 nanocrystals, which have been selectively prepared by solvothermal methods using benzimidazole as a mineralization agent. The sensitivity of as-obtained SnO2 sensor towards 5 ppm H2S can reach up to 357. Such a technique based on SnO2 nanocrystals opens up a promising avenue for future practical applications in real-time monitoring a trace of H2S from the leakage of biogas. PMID:25112163

  9. MIL-53 frameworks in mixed-matrix membranes and cross-linked ZIF-8/matrimidRTM mixed-matrix membranes for gas separation

    NASA Astrophysics Data System (ADS)

    Hsieh, Josephine Ordonez

    Mixed matrix membranes (MMMs) are hybrid materials consisting of two phases: an inorganic nanoscale particle as the discrete phase, and a polymeric material as the continuous phase. The incorporation of inorganic particles into a polymer can improve a membrane's overall separation performance. MMMs incorporating metal-organic frameworks (MOFs) have exhibited promising gas separation performance. MOFs are inorganic-organic crystals constructed from metal ions that are linked by polydentate ligands. Zeolitic imidazolate frameworks (ZIFs) are a sub-class of MOFs that uses imidazole analogues as ligands. In these studies, the MOF MIL-53 and ZIF-8 were successfully synthesized and characterized by a battery of analytical techniques including XRD, FTIR, TGA, N2 adsorption, and SEM, and were incorporated into MMMs with Matrimid® polymer. In chapter 1, MIL-53/Matrimid® MMMs containing MIL-53-ht (open-pore form) were fabricated, characterized and obtained permeability values higher than Matrimid®. Selectivities decreased for the gas pairs of O2/N2, H2/O2, H2/CO2, and H2/N2. However, slight enhancement of the CO2/CH4 selectivity was observed for the MIL-53-ht/Matrimid® compared to that of Matrimid ®. The MIL-53-as/Matrimid® MMM also showed an increase in permeability as well as an increase in selectivity for the gas pairs H2/O2, CO2/CH4, H 2/CH4, and H2/N2. The MIL-53-lt/Matrimid ® MMM showed that it does not retain its closed-pore form in the MMM due to chloroform solvent opening the pores and eventually polymer confinement of the MIL 53 framework in the MMM. In chapter 2, easy synthesis and fabrication of the MIL-53 MOF membrane was realized using a seeded growth method with a commercially available alumina TLC plate. The MOF membrane had a well-intergrown and dense layer of MIL-53 crystals on the surface of the alumina substrate. The MIL-53 crystals were also converted to the MIL-53-lt (closed-pore form) after heating at 330 °C and cooling to room temperature

  10. Large-Flow-Area Flow-Selective Liquid/Gas Separator

    NASA Technical Reports Server (NTRS)

    Vasquez, Arturo; Bradley, Karla F.

    2010-01-01

    This liquid/gas separator provides the basis for a first stage of a fuel cell product water/oxygen gas phase separator. It can separate liquid and gas in bulk in multiple gravity environments. The system separates fuel cell product water entrained with circulating oxygen gas from the outlet of a fuel cell stack before allowing the gas to return to the fuel cell stack inlet. Additional makeup oxygen gas is added either before or after the separator to account for the gas consumed in the fuel cell power plant. A large volume is provided upstream of porous material in the separator to allow for the collection of water that does not exit the separator with the outgoing oxygen gas. The water then can be removed as it continues to collect, so that the accumulation of water does not impede the separating action of the device. The system is designed with a series of tubes of the porous material configured into a shell-and-tube heat exchanger configuration. The two-phase fluid stream to be separated enters the shell-side portion of the device. Gas flows to the center passages of the tubes through the porous material and is then routed to a common volume at the end of the tubes by simple pressure difference from a pumping device. Gas flows through the porous material of the tubes with greater ease as a function of the ratio of the dynamic viscosity of the water and gas. By careful selection of the dimensions of the tubes (wall thickness, porosity, diameter, length of the tubes, number of the tubes, and tube-to-tube spacing in the shell volume) a suitable design can be made to match the magnitude of water and gas flow, developed pressures from the oxygen reactant pumping device, and required residual water inventory for the shellside volume.

  11. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    DOEpatents

    Aines, Roger D.

    2013-03-12

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  12. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    DOEpatents

    Aines, Roger D

    2015-03-31

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  13. Confinement Effects on the Nuclear Spin Isomer Conversion of H2O.

    PubMed

    Turgeon, Pierre-Alexandre; Vermette, Jonathan; Alexandrowicz, Gil; Peperstraete, Yoann; Philippe, Laurent; Bertin, Mathieu; Fillion, Jean-Hugues; Michaut, Xavier; Ayotte, Patrick

    2017-03-02

    The mechanism for interconversion between the nuclear spin isomers (NSI) of H2O remains shrouded in uncertainties. The temperature dependence displayed by NSI interconversion rates for H2O isolated in an argon matrix provides evidence that confinement effects are responsible for the dramatic increase in their kinetics with respect to the gas phase, providing new pathways for o-H2O↔p-H2O conversion in endohedral compounds. This reveals intramolecular aspects of the interconversion mechanism which may improve methodologies for the separation and storage of NSI en route to applications ranging from magnetic resonance spectroscopy and imaging to interpretations of spin temperatures in the interstellar medium.

  14. Enhanced H2 gas production from bagasse using adhE inactivated Klebsiella oxytoca HP1 by sequential dark-photo fermentations.

    PubMed

    Wu, Xiaobing; Li, Qianyi; Dieudonne, Mutangana; Cong, Yibo; Zhou, Juan; Long, Minnan

    2010-12-01

    Sequential dark-photo fermentations (SDPF) was used for hydrogen production from bagasse, an acetaldehyde dehydrogenase (adhE) gene inactivated Klebsiella oxytoca HP1 (DeltaadhE HP1) mutant was used to reduce the alcohol content in dark fermentation (DF) broths and to further enhance the hydrogen yield during the photo fermentation (PF) stage. Compared with that of the wild strain, the ethanol concentration in DF broths of DeltaadhE HP1 decreased 69.4%, which resulted in a hydrogen yield in the PF stage and the total hydrogen yield over the two steps increased by 54.7% and 23.5%, respectively. The culture conditions for hydrogen production from acid pretreated bagasse by SDPF were optimized as culture temperature 37.5 degrees C, initial pH 7.0, and cellulase loading 20 FPA/g in the DF stage, with initial pH 6.5, temperature 30 degrees C and photo intensity 5,000 lux in the PF stage. Under optimum conditions, by using DeltaadhE HP1 and wild type strain, the H(2) yields were 107.8+/-5.3 mL H(2)/g-bagasse, 96.2+/-4.4 mL H(2)/g-bagasse in DF and 54.3+/-2.2 mL H(2)/g-bagasse, 35.1+/-2.0 mL H(2)/g-bagasse in PF, respectively. The special hydrogen production rate (SHPR) were 5.51+/-0.34 mL H(2)/g-bagasseh, 4.95+/-0.22 mL H(2)/g-bagasseh in DF and 0.93+/-0.12 mL H(2)/g-bagasseh, 0.59+/-0.07 mL H(2)/g-bagasseh in PF, respectively. The total hydrogen yield from bagasse over two steps was 162.1+/-7.5 mL H(2)/g-bagasse by using DeltaadhE HP1, which was 50.4% higher than that from dark fermentation only. These results indicate that reducing ethanol content during dark fermentation by using an adhE inactivated strain can significantly enhance hydrogen production from bagasse in the SDPF system. This work also proved that SDPF was an effective way to improve hydrogen production from bagasse.

  15. Characterization of a solvent-separated ion-radical pair in cationized water networks: infrared photodissociation and Ar-attachment experiments for water cluster radical cations (H2O)n+(n = 3-8).

    PubMed

    Mizuse, Kenta; Fujii, Asuka

    2013-02-07

    We present infrared spectra of nominal water cluster radical cations (H(2)O)(n)(+) (n = 3-8), or to be precise, ion-radical complexes H(+)(H(2)O)(n-1)(OH), with and without an Ar tag. These clusters are closely related to the ionizing radiation-induced processes in water and are a good model to characterize solvation structures of the ion-radical pair. The spectra of Ar-tagged species show narrower bandwidths relative to those of the bare clusters due to the reduced internal energy via an Ar-attachment. The observed spectra are analyzed by comparing with those of the similar system, H(+)(H(2)O)(n), and calculated ones. We find that the observed spectra are attributable to ion-radical-separated motifs in n ≥ 5, as reported in the previous study (Mizuse et al. Chem. Sci.2011, 2, 868-876). Beyond the structural trends found in the previous study, we characterize isomeric structures and determine the number of water molecules between the charged site and the OH radical in each cluster size. In all of the characterized cluster structures (n = 5-8), the most favorable position of OH radical is the next neighbor of the charged site (H(3)O(+) or H(5)O(2)(+)). The positions and cluster structures are governed by the balance among the hydrogen-bonding abilities of the charged site, H(2)O, and OH radical. These findings on the ionized water networks lead to understanding of the detailed processes of ionizing radiation-initiated reactions in liquid water and aqueous solutions.

  16. Dynamic graphene filters for selective gas-water-oil separation.

    PubMed

    Bong, Jihye; Lim, Taekyung; Seo, Keumyoung; Kwon, Cho-Ah; Park, Ju Hyun; Kwak, Sang Kyu; Ju, Sanghyun

    2015-09-23

    Selective filtration of gas, water, and liquid or gaseous oil is essential to prevent possible environmental pollution and machine/facility malfunction in oil-based industries. Novel materials and structures able to selectively and efficiently filter liquid and vapor in various types of solutions are therefore in continuous demand. Here, we investigate selective gas-water-oil filtration using three-dimensional graphene structures. The proposed approach is based on the adjustable wettability of three-dimensional graphene foams. Three such structures are developed in this study; the first allows gas, oil, and water to pass, the second blocks water only, and the third is exclusively permeable to gas. In addition, the ability of three-dimensional graphene structures with a self-assembled monolayer to selectively filter oil is demonstrated. This methodology has numerous potential practical applications as gas, water, and/or oil filtration is an essential component of many industries.

  17. Dynamic graphene filters for selective gas-water-oil separation

    NASA Astrophysics Data System (ADS)

    Bong, Jihye; Lim, Taekyung; Seo, Keumyoung; Kwon, Cho-Ah; Park, Ju Hyun; Kwak, Sang Kyu; Ju, Sanghyun

    2015-09-01

    Selective filtration of gas, water, and liquid or gaseous oil is essential to prevent possible environmental pollution and machine/facility malfunction in oil-based industries. Novel materials and structures able to selectively and efficiently filter liquid and vapor in various types of solutions are therefore in continuous demand. Here, we investigate selective gas-water-oil filtration using three-dimensional graphene structures. The proposed approach is based on the adjustable wettability of three-dimensional graphene foams. Three such structures are developed in this study; the first allows gas, oil, and water to pass, the second blocks water only, and the third is exclusively permeable to gas. In addition, the ability of three-dimensional graphene structures with a self-assembled monolayer to selectively filter oil is demonstrated. This methodology has numerous potential practical applications as gas, water, and/or oil filtration is an essential component of many industries.

  18. Phase separation in a polarized Fermi gas with spin-orbit coupling

    SciTech Connect

    Yi, W.; Guo, G.-C.

    2011-09-15

    We study the phase separation of a spin-polarized Fermi gas with spin-orbit coupling near a wide Feshbach resonance. As a result of the competition between spin-orbit coupling and population imbalance, the phase diagram for a uniform gas develops a rich structure of phase separation involving topologically nontrivial gapless superfluid states. We then demonstrate the phase separation induced by an external trapping potential and discuss the optimal parameter region for the experimental observation of the gapless superfluid phases.

  19. Evolution of Structure and Electrical Characteristics of Pt/WOx/6H-SiC Sensor Upon Exposure to H2 Gas at High Temperature

    NASA Astrophysics Data System (ADS)

    Zuev, V. V.; Demin, M. V.; Fominski, V. Yu.; Romanov, R. I.

    The bilayer film Pt/WOx was deposited by pulsed laser ablation on a silicon carbide monocrystal plate (6H-SiC) to form an H2 sensor for high temperature application. The study demonstrates high sensitivity of the Pt/WOx/SiC structure to a low H2 concentration. For 0.2 H2% in air at 350 °C, the shift of voltage on the reverse branch of the current-voltage characteristic reached 6.5 V at a current of 0.4 μA. After the high temperature interaction with H2, the sample can confine hydrogen atoms in the WOx layer at room temperature for a long time. The study explores the influence of operation conditions as well as the H2 action on the structure and electrical characteristics of the layers in the system. Phase transformation of the crystalline structure of the WOx film due to hydrogen penetration was detected and this process initiated pronounced electrical properties changes.

  20. Biogeochemistry of dihydrogen (H2).

    PubMed

    Hoehler, Tori M

    2005-01-01

    of water-rock interaction could have supported an early chemosynthetic biosphere. Such processes offer the continued potential for a deep, rock-hosted biosphere on Earth or other bodies in the solar system. The continued evolution of metabolic and community-level versatility among microbes led to an expanded ability to completely exploit the energy available in complex organic matter. Under the anoxic conditions that prevailed on the early Earth, this was accomplished through the linked and sequential action of several metabolic classes of organisms. By transporting electrons between cells, H2 provides a means of linking the activities of these organisms into a highly functional and interactive network. At the same time, H2 concentrations exert a powerful thermodynamic control on many aspects of metabolism and biogeochemical function in these systems. Anaerobic communities based on the consumption of organic matter continue to play an important role in global biogeochemistry even into the present day. As the principal arbiters of chemistry in most aquatic sediments and animal digestive systems, these microbes affect the redox and trace-gas chemistry of our oceans and atmosphere, and constitute the ultimate biological filter on material passing into the rock record. It is in such communities that the significance of H2 in mediating biogeochemical function is most strongly expressed. The advent of phototrophic metabolism added another layer of complexity to microbial communities, and to the role of H2 therein. Anoxygenic and oxygenic phototrophs retained and expanded on the utilization of H2 in metabolic processes. Both groups produce and consume H2 through a variety of mechanisms. In the natural world, phototrophic organisms are often closely juxtaposed with a variety of other metabolic types, through the formation of biofilms and microbial mats. In the few examples studied, phototrophs contribute an often swamping term to the H2 economy of these communities, with

  1. Cooler and particulate separator for an off-gas stack

    DOEpatents

    Wright, G.T.

    1991-04-08

    This report describes an off-gas stack for a melter, furnace or reaction vessel comprising an air conduit leading to two sets of holes, one set injecting air into the off-gas stack near the melter plenum and the second set injecting air downstream of the first set. The first set injects air at a compound angle, having both downward and tangential components, to create a reverse vortex flow, counter to the direction of flow of gas through the stack and also along the periphery of the stack interior surface. Air from the first set of holes prevents recirculation zones from forming and the attendant accumulation of particulate deposits on the wall of the stack and will also return to the plenum any particulate swept up in the gas entering the stack. The second set of holes injects air in the same direction as the gas in the stack to compensate for the pressure drop and to prevent the concentration of condensate in the stack. A set of sprayers, receiving water from a second conduit, is located downstream of the second set of holes and sprays water into the gas to further cool it.

  2. Cooler and particulate separator for an off-gas stack

    DOEpatents

    Wright, George T.

    1992-01-01

    An off-gas stack for a melter comprising an air conduit leading to two sets of holes, one set injecting air into the off-gas stack near the melter plenum and the second set injecting air downstream of the first set. The first set injects air at a compound angle, having both downward and tangential components, to create a reverse vortex flow, counter to the direction of flow of gas through the stack and also along the periphery of the stack interior surface. Air from the first set of holes pervents recirculation zones from forming and the attendant accumulation of particulate deposits on the wall of the stack and will also return to the plenum any particulate swept up in the gas entering the stack. The second set of holes injects air in the same direction as the gas in the stack to compensate for the pressure drop and to prevent the concentration of condensate in the stack. A set of sprayers, receiving water from a second conduit, is located downstream of the second set of holes and sprays water into the gas to further cool it.

  3. Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas

    SciTech Connect

    Baker, R.W.; Bell, C.M.; Chow, P.; Louie, J.; Mohr, J.M.; Peinemann, K.V.; Pinnau, I.; Wijmans, J.G.; Gottschlich, D.E.; Roberts, D.L.

    1990-10-01

    The production of hydrogen from synthesis gas made by gasification of coal is expensive. The separation of hydrogen from synthesis gas is a major cost element in the total process. In this report we describe the results of a program aimed at the development of membranes and membrane modules for the separation and purification of hydrogen from synthesis gas. The performance properties of the developed membranes were used in an economic evaluation of membrane gas separation systems in the coal gasification process. Membranes tested were polyetherimide and a polyamide copolymer. The work began with an examination of the chemical separations required to produce hydrogen from synthesis gas, identification of three specific separations where membranes might be applicable. A range of membrane fabrication techniques and module configurations were investigated to optimize the separation properties of the membrane materials. Parametric data obtained were used to develop the economic comparison of processes incorporating membranes with a base-case system without membranes. The computer calculations for the economic analysis were designed and executed. Finally, we briefly investigated alternative methods of performing the three separations in the production of hydrogen from synthesis gas. The three potential opportunities for membranes in the production of hydrogen from synthesis gas are: (1) separation of hydrogen from nitrogen as the final separation in a air-blown or oxygen-enriched air-blown gasification process, (2) separation of hydrogen from carbon dioxide and hydrogen sulfide to reduce or eliminate the conventional ethanolamine acid gas removal unit, and (3) separation of hydrogen and/or carbon dioxide form carbon monoxide prior to the shift reactor to influence the shift reaction. 28 refs., 54 figs., 40 tabs.

  4. Separation and characterization of the two diastereomers for [Gd(DTPA-bz-NH2)(H2O)]2-, a common synthon in macromolecular MRI contrast agents: their water exchange and isomerization kinetics.

    PubMed

    Burai, László; Tóth, Eva; Sour, Angélique; Merbach, André E

    2005-05-16

    Chiral, bifunctional poly(amino carboxylate) ligands are commonly used for the synthesis of macromolecular, Gd(III)-based MRI contrast agents, prepared in the objective of increasing relaxivity or delivering the paramagnetic Gd(III) to a specific site (targeting). Complex formation with such ligands results in two diastereomeric forms for the complex which can be separated by HPLC. We demonstrated that the diastereomer ratio for Ln(III) DTPA derivatives (approximately 60:40) remains constant throughout the lanthanide series, in contrast to Ln(III) EPTPA derivatives, where it varies as a function of the cation size with a maximum for the middle lanthanides (DTPA(5-) = diethylenetriaminepentaacetate; EPTPA(5-) = ethylenepropylenetriaminepentaacetate). The interconversion of the two diastereomers, studied by HPLC, is a proton-catalyzed process (k(obs) = k(1)[H(+)]). It is relatively fast for [Gd(EPTPA-bz-NH(2))(H(2)O)](2-) but slow enough for [Gd(DTPA-bz-NH(2))(H(2)O)](2-) to allow investigation of pure individual isomers (isomerization rate constants are k(1) = (3.03 +/- 0.07) x 10(4) and 11.6 +/- 0.5 s(-1) M(-1) for [Gd(EPTPA-bz-NH(2))(H(2)O)](2)(-) and [Gd(DTPA-bz-NH(2))(H(2)O)](2-), respectively). Individual water exchange rates have been determined for both diastereomers of [Gd(DTPA-bz-NH(2))(H(2)O)](2-) by a variable-temperature (17)O NMR study. Similarly to Ln(III) EPTPA derivatives, k(ex) values differ by a factor of 2 (k(ex)(298) = (5.7 +/- 0.2) x 10(6) and (3.1 +/- 0.1) x 10(6) s(-1)). This variance in the exchange rate has no consequence on the proton relaxivity of the two diastereomers, since it is solely limited by fast rotation. However, such difference in k(ex) will affect proton relaxivity when these diastereomers are linked to a slowly rotating macromolecule. Once the rotation is optimized, slow water exchange will limit relaxivity; thus, a factor of 2 in the exchange rate can lead to a remarkably different relaxivity for the diastereomer complexes

  5. Gas chromatographic separation of hydrogen isotopes using metal hydrides

    SciTech Connect

    Aldridge, F.T.

    1984-05-09

    A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

  6. Stratospheric H2O

    NASA Technical Reports Server (NTRS)

    Ellsaesser, H. W.; Harries, J. E.; Kley, D.; Penndorf, R.

    1980-01-01

    The present state of our knowledge and understanding of H2O in the stratosphere is reviewed. This reveals continuing discrepancies between observations and expectations following from the Brewer-Dobson hypothesis of stratospheric circulation. In particular, available observations indicate unexplained upward and poleward directed H2O gradients immediately downstream from the tropical tropopause and variable vertical gradients above 20 km which generally disagree with those expected from oxidation of CH4.

  7. Blends of a Polymer of Intrinsic Microporosity and Partially Sulfonated Polyphenylenesulfone for Gas Separation.

    PubMed

    Yong, Wai Fen; Lee, Zhi Kang; Chung, Tai-Shung; Weber, Martin; Staudt, Claudia; Maletzko, Christian

    2016-08-09

    Polyphenylenesulfone (PPSU) and sulfonated polyphenylenesulfone (sPPSU) are widely used for liquid separations in the medical and food industries. However, their potential applications for gas separation have not been studied extensively owing to their low intrinsic gas permeability. We report here for the first time that blending with sPPSU can significantly improve the gas separation performance of highly permeable polymers of intrinsic microporosity (PIMs), specifically PIM-1, because of the strong molecular interactions of the sulfonic acid groups of sPPSU with CO2 and O2 . In addition, a novel co-solvent system has been discovered to overcome the immiscibility of these polymers. The presence of a higher degree of sulfonation in sPPSU results in better gas separation performance of the blend membranes close to or above the Robeson upper bound lines for O2 /N2 , CO2 /N2 and CO2 /CH4 separations. Interestingly, the blend membranes have comparable gas selectivity to sPPSU even though their sPPSU content is only 5-20 wt %. Moreover, they also display improved anti-plasticization properties up to 30 atm (3 MPa) using a binary CO2 /CH4 feed gas. The newly developed PIM-1/sPPSU membranes are potential candidates for air separation, natural gas separation, and CO2 capture.

  8. Gas-aerosol relationships of H2SO4, MSA, and OH: Observations in the coastal marine boundary layer at Mace Head, Ireland

    NASA Astrophysics Data System (ADS)

    Berresheim, H.; Elste, T.; Tremmel, H. G.; Allen, A. G.; Hansson, H.-C.; Rosman, K.; Dal Maso, M.; MäKelä, J. M.; Kulmala, M.; O'Dowd, C. D.

    2002-10-01

    Atmospheric concentrations of gaseous sulfuric acid (H2SO4), methane sulfonic acid (MSA), and hydroxyl radicals (OH) were measured by chemical ionization mass spectrometry (CIMS) during the second New Particle Formation and Fate in the Coastal Environment (PARFORCE) campaign in June 1999 at Mace Head, Ireland. Overall median concentrations in marine background air were 1.5, 1.2, and 0.12 × 106 cm-3, respectively. H2SO4 was also present at night indicating significant contributions from nonphotochemical sources. A strong correlation was found between daytime OH and H2SO4 levels in clean marine air suggesting a fast local production of H2SO4 from sulfur precursor gases. Steady state balance calculations of ambient H2SO4 levels agreed with measured concentrations if either very low H2SO4 sticking coefficients (0.02-0.03) or sources in addition to the SO2 + OH reaction were assumed. Overall, variations in ambient H2SO4 levels showed no correlation with either the tidal cycle or ultrafine particle (UFP) concentrations. However, on particular days an anticorrelation between H2SO4 and UFP levels was occasionally observed providing evidence for the contribution of H2SO4 to new particle formation and/or particle growth. Gaseous MSA concentrations were inversely correlated with dew point temperature reflecting a highly sensitive gas-particle partitioning equilibrium of this compound. The present observations seriously question the general use of MSA as a conservative tracer to infer the relative production yield of H2SO4 from dimethylsulfide (DMS) oxidation. MSA/H2SO4 concentration ratios typically ranged between 0.06 and 1.0 in marine air at ground level. Measured diel OH profiles showed a significant deviation from concurrent variations of the ozone photolysis frequency. They also showed up to 1 order of magnitude lower values compared to OH concentrations calculated with a simple photochemical box model. These differences were most pronounced during particle nucleation

  9. ELECTROCHEMICAL SEPARATION AND CONCENTRATION OF HYDROGEN SULFIDE FROM GAS MIXTURES

    DOEpatents

    Winnick, Jack; Sather, Norman F.; Huang, Hann S.

    1984-10-30

    A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

  10. Electrochemical separation and concentration of hydrogen sulfide from gas mixtures

    DOEpatents

    Winnick, Jack; Sather, Norman F.; Huang, Hann S.

    1984-10-30

    A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

  11. Catalytic ethanolysis and gasification of kraft lignin into aromatic alcohols and H2-rich gas over Rh supported on La2O3/CeO2-ZrO2.

    PubMed

    Yang, Jing; Zhao, Liang; Liu, Chunze; Wang, Yuanyuan; Dai, Liyi

    2016-10-01

    Efficient catalytic ethanolysis and gasification of kraft lignin were conducted over a versatile supported catalyst Rh/La2O3/CeO2-ZrO2 to give high-value aromatic alcohols and H2-rich gas. The removal of phenolic hydroxyl group was the most prevalent reaction, and importantly, almost no phenols, undesired char and saturating the aromatic ring were detected. Meanwhile, the feedstock and solvent both played key roles in H2 generation that contributed to the hydrodeoxygenation of liquid components and made the whole catalytic process out of H2 supply. Reusability tests of catalyst indicated that the crystalline phase transition and agglomeration of support, the loss of noble metal Rh and carbon deposition were the possible reasons for its deactivation in supercritical ethanol. Comparing with water, methanol and isopropanol system, ethanol was the only effective solvent for the depolymerization process.

  12. One Step Biomass Gas Reforming-Shift Separation Membrane Reactor

    SciTech Connect

    Roberts, Michael J.; Souleimanova, Razima

    2012-12-28

    GTI developed a plan where efforts were concentrated in 4 major areas: membrane material development, membrane module development, membrane process development, and membrane gasifier scale-up. GTI assembled a team of researchers to work in each area. Task 1.1 Ceramic Membrane Synthesis and Testing was conducted by Arizona State University (ASU), Task 1.2 Metallic Membrane Synthesis and Testing was conducted by the U.S. National Energy Technology Laboratory (NETL), Task 1.3 was conducted by SCHOTT, and GTI was to test all membranes that showed potential. The initial focus of the project was concentrated on membrane material development. Metallic and glass-based membranes were identified as hydrogen selective membranes under the conditions of the biomass gasification, temperatures above 700C and pressures up to 30 atmospheres. Membranes were synthesized by arc-rolling for metallic type membranes and incorporating Pd into a glass matrix for glass membranes. Testing for hydrogen permeability properties were completed and the effects of hydrogen sulfide and carbon monoxide were investigated for perspective membranes. The initial candidate membrane of Pd80Cu20 chosen in 2008 was selected for preliminary reactor design and cost estimates. Although the H2A analysis results indicated a $1.96 cost per gge H2 based on a 5A (micron) thick PdCu membrane, there was not long-term operation at the required flux to satisfy the go/no go decision. Since the future PSA case yielded a $2.00/gge H2, DOE decided that there was insufficient savings compared with the already proven PSA technology to further pursue the membrane reactor design. All ceramic membranes synthesized by ASU during the project showed low hydrogen flux as compared with metallic membranes. The best ceramic membrane showed hydrogen permeation flux of 0.03 SCFH/ft2 at the required process conditions while the metallic membrane, Pd80Cu20 showed a flux of 47.2 SCFH/ft2 (3 orders of magnitude difference). Results from

  13. Systems and methods for using a boehmite bond-coat with polyimide membranes for gas separation

    DOEpatents

    Polishchuk, Kimberly Ann

    2013-03-05

    The subject matter disclosed herein relates to gas separation membranes and, more specifically, to polyimide gas separation membranes. In an embodiment, a gas separation membrane includes a porous substrate, a substantially continuous polyimide membrane layer, and one or more layers of boehmite nanoparticles disposed between the porous substrate and the polyimide membrane layer to form a bond-coat layer. The bond-coat layer is configured to improve the adhesion of the polyimide membrane layer to the porous substrate, and the polyimide membrane layer has a thickness approximately 100 nm or less.

  14. Predicting possible effects of H2S impurity on CO2 transportation and geological storage.

    PubMed

    Ji, Xiaoyan; Zhu, Chen

    2013-01-02

    For CO(2) geological storage, permitting impurities, such as H(2)S, in CO(2) streams can lead to a great potential for capital and energy savings for CO(2) capture and separation, but it also increases costs and risk management for transportation and storage. To evaluate the cost-benefits, using a recently developed model (Ji, X.; Zhu, C. Geochim. Cosmochim. Acta 2012, 91, 40-59), this study predicts phase equilibria and thermodynamic properties of the system H(2)S-CO(2)-H(2)O-NaCl under transportation and storage conditions and discusses potential effects of H(2)S on transportation and storage. The prediction shows that inclusion of H(2)S in CO(2) streams may lead to two-phase flow. For H(2)S-CO(2) mixtures, at a given temperature, the bubble and dew pressures decrease with increasing H(2)S content, while the mass density increases at low pressures and decreases at high pressures. For the CO(2)-H(2)S-H(2)O system, the total gas solubility increases while the mass density of the aqueous solution with dissolved gas decreases. For the CO(2)-H(2)S-H(2)O-NaCl system, at a given temperature, pressure and NaCl concentration, the solubility of the gas mixture in aqueous phase increases with increasing H(2)S content and then decreases, while the mass density of aqueous solution decreases and may be lower than the mass density of the solution without gas dissolution.

  15. Cellulose triacetate doped with ionic liquids for membrane gas separation

    NASA Astrophysics Data System (ADS)

    Lam, Benjamin Fatt Soon

    The doping of cellulose triacetate (CTA) with imidazolium based ionic liquids (ILs) is investigated in order to reduce the polymer crystallinity and enhance the affinity with CO2, thus increasing CO2 permeability and CO2/light gas selectivity. CTA membranes doped with [emim] BF4 or [emim] DCA were prepared, and the effect of the ILs loading on properties, such as crystallinity, density, degradation temperature, glass transition temperature, and gas transport properties, has been determined. In general, doping with IL reduces the crystallinity in CTA, increasing gas solubility, diffusivity and permeability. The ILs doping also increases CO 2/CH4 solubility selectivity and CO2/N2 permeability selectivity, due to the affinity of these ILs with CO2, instead of light gases such as CH4 and N2. This study provides a mechanistic understanding of interaction of ILs and CTA, and demonstrates an effective route in manipulating the morphology and gas transport properties of semi crystalline polymers by doping with ILs.

  16. Membrane-Based Gas Separation Accelerated by Hollow Nanosphere Architectures

    SciTech Connect

    Zhang, Jinshui; Schott, Jennifer Ann; Li, Yunchao; Zhan, Wangcheng; Mahurin, Shannon M.; Nelson, Kimberly; Sun, Xiao-Guang; Paranthaman, Mariappan Parans; Dai, Sheng

    2016-11-15

    We report that the coupling of hollow carbon nanospheres with triblock copolymers is a promising strategy to fabricate mixed-matrix membranes, because the symmetric microporous shells combine with the hollow space to promote gas transport and the unique soft-rigid molecular structure of triblock copolymers can accommodate a high loading of fillers without a significant loss of mechanical strength.

  17. Flexible metal–organic supramolecular isomers for gas separation

    SciTech Connect

    Motkuri, Radha K.; Tian, Jian; Thallapally, Praveen K.; Fernandez, Carlos A.; Dalgarno, Scott J.; Warren, John E.; McGrail, B. Peter; Atwood, Jerry L.

    2010-01-01

    Here in we report three porous metal-organic supramolecular isomers (PtS, Diamondoid and Lonsdaleite networks) generated from a single building block (tetrakis[4-(carboxyphenyl)oxamethyl]methane, 1), with the differences in solid-state packing, amount of gas uptake and selectivity towards other gases and so on

  18. Gas chromatography-mass spectrometric analysis of oxidative reactions of [19,19-(2)H(2)]19-hydroxy-3-deoxy androgens by placental aromatase. bsence of a deuterium-isotope effect.

    PubMed

    Nagaoka, Masao; Numazawa, Mitsuteru

    2005-11-01

    Aromatase is a cytochrome P-450 enzyme complex that catalyzes the conversion of androst-4-ene-3,17-dione (AD) to estrone through three sequential oxidations of the 19-methyl group. 3-DeoxyAD (1) and its 5-ene isomer 4 are potent and good competitive aromatase inhibitors, which are converted by aromatase to the aldehyde derivatives 3 and 6, respectively, through 19-hydroxy intermediates 2 and 5, respectively. To study the deuterium isotope effect on the conversions of 19-ols 2 and 5 into the corresponding 19-als 3 and 6, we initially synthesized [19,19-(2)H(2)]19-ols 2 and 5 starting from the corresponding non-labeled 19-als 3 and 6 through NaB(2)H(4) reduction of the 19-aldehyde group, followed by oxidation with pyridinium dichromate, and a subsequent NaB(2)H(4) reduction. Approximately 1:1 mixtures of non-labeled (d(0)) and deuterated (d(2)) 19-ols 2 and 5 were separately incubated with human placental microsomes in the presence of NADPH under an air atmosphere, and deuterium contents of the recovered substrates and the 19-aldehyde products were determined by gas chromatography-mass spectrometry. In each experiment, the ratio of d(0) to d(2) of the recovered substrate along with that of d(0) to d(1) of the product were identical to the d(0) to d(2) ratio of the employed substrate irrespective of the incubation time, indicating that the 19-oxygenations of the 3-deoxy steroids 2 and 5 proceeded without a detectable isotope effect, as seen in the aromatization sequence of the natural substrate AD.

  19. Gas Separation Using Organic-Vapor-Resistent Membranes In Conjunctin With Organic-Vapor-Selective Membranes

    DOEpatents

    Baker, Richard W.; Pinnau, Ingo; He, Zhenjie; Da Costa, Andre R.; Daniels, Ramin; Amo, Karl D.; Wijmans, Johannes G.

    2003-06-03

    A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other selective for the second gas over the organic vapor. The second-gas-selective membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons. The membrane steps can be combined in either order.

  20. UTSA-74: A MOF-74 Isomer with Two Accessible Binding Sites per Metal Center for Highly Selective Gas Separation.

    PubMed

    Luo, Feng; Yan, Changsheng; Dang, Lilong; Krishna, Rajamani; Zhou, Wei; Wu, Hui; Dong, Xinglong; Han, Yu; Hu, Tong-Liang; O'Keeffe, Michael; Wang, Lingling; Luo, Mingbiao; Lin, Rui-Biao; Chen, Banglin

    2016-05-04

    A new metal-organic framework Zn2(H2O)(dobdc)·0.5(H2O) (UTSA-74, H4dobdc = 2,5-dioxido-1,4-benzenedicarboxylic acid), Zn-MOF-74/CPO-27-Zn isomer, has been synthesized and structurally characterized. It has a novel four coordinated fgl topology with one-dimensional channels of about 8.0 Å. Unlike metal sites in the well-established MOF-74 with a rod-packing structure in which each of them is in a five coordinate square pyramidal coordination geometry, there are two different Zn(2+) sites within the binuclear secondary building units in UTSA-74 in which one of them (Zn1) is in a tetrahedral while another (Zn2) in an octahedral coordination geometry. After activation, the two axial water molecules on Zn2 sites can be removed, generating UTSA-74a with two accessible gas binding sites per Zn2 ion. Accordingly, UTSA-74a takes up a moderately high and comparable amount of acetylene (145 cm(3)/cm(3)) to Zn-MOF-74. Interestingly, the accessible Zn(2+) sites in UTSA-74a are bridged by carbon dioxide molecules instead of being terminally bound in Zn-MOF-74, so UTSA-74a adsorbs a much smaller amount of carbon dioxide (90 cm(3)/cm(3)) than Zn-MOF-74 (146 cm(3)/cm(3)) at room temperature and 1 bar, leading to a superior MOF material for highly selective C2H2/CO2 separation. X-ray crystal structures, gas sorption isotherms, molecular modeling, and simulated and experimental breakthroughs comprehensively support this result.

  1. Catalytic oxidation of H2 by N2O in the gas phase: O-atom transport with atomic metal cations.

    PubMed

    Blagojevic, Voislav; Bozović, Andrea; Orlova, Galina; Bohme, Diethard K

    2008-10-16

    Twenty-five atomic cations, M (+), that lie within the thermodynamic window for O-atom transport catalysis of the oxidation of hydrogen by nitrous oxide, have been checked for catalytic activity at room temperature with kinetic measurements using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. Only 4 of these 25 atomic cations were seen to be catalytic: Fe (+), Os (+), Ir (+), and Pt (+). Two of these, Ir (+) and Pt (+), are efficient catalysts, while Fe (+) and Os (+) are not. Eighteen atomic cations (Cr (+), Mn (+), Co (+), Ni (+), Cu (+), Ge (+), Se (+), Mo (+), Ru (+), Rh (+), Sn (+), Te (+), Re (+), Pb (+), Bi (+), Eu (+), Tm (+), and Yb (+)) react too slowly at room temperature either in their oxidation with N 2O to form MO (+) or in the reduction of MO (+) by H 2. Many of these reactions are known to be spin forbidden and a few actually may lie outside the thermodynamic window. Three alkaline-earth metal monoxide cations, CaO (+), SrO (+), and BaO (+), were observed to favor MOH (+) formation in their reactions with H 2. A potential-energy landscape is computed for the oxidation of H 2 with N 2O catalyzed by Fe (+)( (6)D) that vividly illustrates the operation of an ionic catalyst and qualitatively accounts for the relative inefficiency of this catalyst.

  2. Solid H2 versus solid noble-gas environment: Influence on photoinduced hydrogen-atom transfer in matrix-isolated 4(3H)-pyrimidinone

    NASA Astrophysics Data System (ADS)

    Lapinski, Leszek; Nowak, Maciej J.; Rostkowska, Hanna

    2017-03-01

    UV-induced transformations have been studied for 4(3H)-pyrimidinone monomers isolated in low-temperature Ar, Ne, n-D2, and n-H2 matrices. The observed photochemical behavior of the compound drastically depended on the solid matrix environment. For 4(3H)-pyrimidinone isolated in solid Ar, the UV-induced phototautomeric transformation was clearly the dominating process, leading to a nearly quantitative conversion of the oxo reactant into the hydroxy product. For solid Ne environment, the oxo → hydroxy transformation was still the major photoprocess, but yielding less of the hydroxy product (ca. 64% of the yield in solid Ar). For 4(3H)-pyrimidinone isolated in solid n-H2, the oxo → hydroxy phototautomeric conversion did not occur (or occurred at a very tiny scale). Also for deuterated 4(3D)-pyrimidinone isolated in solid hydrogen, the analogous oxo → deuteroxy phototransformation was not observed. Finally, for the compound trapped in solid n-D2, the oxo → hydroxy phototautomerism clearly occurred, but the yield of the hydroxy tautomer was small (ca. 18% of the yield in solid Ar). Apart from hydrogen-atom-transfer processes, two other phototransformations: generation of open-ring conjugated ketene and valence Dewar isomer were observed for the compound isolated in Ar, Ne, n-D2, and n-H2 matrices.

  3. Noble-gas-rich separates from ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Moniot, R. K.

    1980-02-01

    Acid-resistant residues were prepared by HCl-HF demineralization of three H-type ordinary chondrites: Brownfield 1937 (H3), Dimmitt (H3, 4), and Estacado (H6). These residues were found to contain a large proportion of the planetary-type trapped Ar, Kr, and Xe in the meteorites. The similarity of these acid residues to those from carbonaceous chondrites and LL-type ordinary chondrites suggests that the same phase carries the trapped noble gases in all these diverse meteorite types. Because the H group represents a large fraction of all meteorites, this result indicates that the gas-rich carrier phase is as universal as the trapped noble-gas component itself. When treated with an oxidizing etchant, the acid residues lost almost all their complement of noble gases.

  4. Postextraction Separation, On-Board Storage, and Catalytic Conversion of Methane in Natural Gas: A Review.

    PubMed

    Saha, Dipendu; Grappe, Hippolyte A; Chakraborty, Amlan; Orkoulas, Gerassimos

    2016-10-12

    In today's perspective, natural gas has gained considerable attention, due to its low emission, indigenous availability, and improvement in the extraction technology. Upon extraction, it undergoes several purification protocols including dehydration, sweetening, and inert rejection. Although purification is a commercially established technology, several drawbacks of the current process provide an essential impetus for developing newer separation protocols, most importantly, adsorption and membrane separation. This Review summarizes the needs of natural gas separation, gives an overview of the current technology, and provides a detailed discussion of the progress in research on separation and purification of natural gas including the benefits and drawbacks of each of the processes. The transportation sector is another growing sector of natural gas utilization, and it requires an efficient and safe on-board storage system. Compressed natural gas (CNG) and liquefied natural gas (LNG) are the most common forms in which natural gas can be stored. Adsorbed natural gas (ANG) is an alternate storage system of natural gas, which is advantageous as compared to CNG and LNG in terms of safety and also in terms of temperature and pressure requirements. This Review provides a detailed discussion on ANG along with computation predictions. The catalytic conversion of methane to different useful chemicals including syngas, methanol, formaldehyde, dimethyl ether, heavier hydrocarbons, aromatics, and hydrogen is also reviewed. Finally, direct utilization of methane onto fuel cells is also discussed.

  5. Noble-gas-rich separates from the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Ott, U.; Mack, R.; Chang, S.

    1981-01-01

    Predominantly carbonaceous HF/HCl-resistant residues from the Allende meteorite are studied. Samples are characterized by SEM/EDXA, X-ray diffraction, INAA, C, S, H, N, and noble gas analyses. Isotopic data for carbon show variations no greater than 5%, while isotopic data from noble gases confirm previously established systematics. Noble gas abundances correlate with those of C and N, and concomitant partial loss of C and normal trapped gas occur during treatments with oxidizing acids. HF/HCl demineralization of bulk meteorite results in similar fractional losses of C and trapped noble gases, which leads to the conclusion that various macromolecular carbonaceous substances serve as the main host phase for normal trapped noble gases and anomalous gases in acid-resistant residues, and as the carrier of the major part of trapped noble gases lost during HF/HCl demineralization. Limits on the possible abundances of dense mineralic host phases in the residues are obtained, and considerations of the nucleogenetic origin for CCF-XE indicate that carbonaceous host phases and various forms of organic matter in carbonaceous meteorites may have a presolar origin.

  6. Separation Characteristics of Heavy Metal Compounds by Hot Gas Cleaning System

    SciTech Connect

    Sakano, T.; Kanaoka, C.; Furuuchi, M.; Yang, K-S.; Hata, M.

    2002-09-20

    The purpose of this research is the basic study for the development of separation technology of heavy metal compounds from hot flue gas. While the hot flue gas containing heavy metals from a melting furnace of industrial waste passes through the high temperature dust collector which can be varied the operating temperature. The heavy metals can be separated due to different boiling point of each heavy metal. On the basis of this concept, the concentration of heavy metals in the flue gas were sampled and measured at inlet, outlet of the ceramic filter housing in the actual industrial waste processing system. Speciation of heavy metals in collected ashes was clarified by separating heavy metals according to compounds using their elution characteristics. Moreover, equilibrium analysis was performed to determine the effect of temperature, flue gases conditions on heavy metals speciation, and it was compared with experimental data. From these results, we discussed about separation performance of heavy metal compounds by hot gas cleaning.

  7. Stability of the liquid particles separation in the apparatus of oil and gas systems

    NASA Astrophysics Data System (ADS)

    Vasilevsky, M. V.; Zyatikov, P. N.; Burykin, A. Y.; Deeva, V. S.

    2015-11-01

    The article considers the methods of associated gas purification from liquid particles. The sintering of liquid particles occurs during the separation process and the trapped droplets can be removed as a liquid stream, i.e. there is no need for unloading units. The droplet size depends on the energy input during their fragmentation. The efficiency of drops separation depends on the flow rate and the intensification of droplets coalescence, film formation and liquid flow to the receiver. The dispersion of the liquid particles is the main drawback of the existing purification methods, i.e. lack of sustainability of particle separation. The comparison of the separation system methods and the devices with flow control elements is carried out. The estimation of gas purification efficiency is conducted. It is concluded that the efficiency of associated gas purification gives the possibility to use it in turbine generators, heating furnaces, etc. It significantly reduces the proportion of gas being flared.

  8. Porous ctn-type boron imidazolate framework for gas storage and separation.

    PubMed

    Zhang, Hai-Xia; Fu, Hong-Ru; Li, Hong-Yan; Zhang, Jian; Bu, Xianhui

    2013-08-26

    BIFing it up: The assembly between triangular HB(mim)3 units and tetrahedral Zn centers (see graphic) leads to the formation of a ctn-type BIF material with high porosity for gas storage and separation (mim = 2-methylimidazolate).

  9. Tunable composite membranes for gas separations. Quarterly technical progress report, May--July 1996

    SciTech Connect

    Ferraris, J.P.; Balkus, K.J. Jr.; Musselman, I.H.

    1996-08-05

    Significant progress has been made in the synthesis and characterization of conducting polymer composite membranes for gas separations. Zeolite/polyalkylthiophene composite membranes have been prepared and characterized for zeolite NaY.

  10. Porous Metal-Organic Frameworks for Gas Storage and Separation: What, How, and Why?

    PubMed

    Li, Bin; Wen, Hui-Min; Zhou, Wei; Chen, Banglin

    2014-10-16

    Metal-organic frameworks (MOFs) have been emerging as promising multifunctional materials and have shown particularly useful applications for gas storage and separation. We have briefly outlined the early development of this very active research field to provide us a clear picture on what are MOFs and how the research endeavor has been initiated and explored. Following that, we have demonstrated why MOFs are so unique for gas storage and separation: high porosities, tunable framework structures, and immobilized functional sites to fully make use of pore space for gas storage, to optimize their sieving effects, and to differentiate their interactions with gas molecules. Finally, we have provided a perspective on further development of porous MOFs for gas storage and separation.

  11. Computational study of the CF4 /CHF3 / H2 /Cl2 /O2 /HBr gas phase plasma chemistry

    NASA Astrophysics Data System (ADS)

    Tinck, Stefan; Bogaerts, Annemie

    2016-05-01

    A modelling study is performed of high-density low-pressure inductively coupled CF4/CHF3/H2/Cl2/O2/HBr plasmas under different gas mixing ratios. A reaction set describing the complete plasma chemistry is presented and discussed. The gas fraction of each component in this mixture is varied to investigate the sensitivity of the plasma properties, like electron density, plasma potential and species densities, towards the gas mixing ratios. This research is of great interest for microelectronics applications because these gases are often combined in two (or more)-component mixtures, and mixing gases or changing the fraction of a gas can sometimes yield unwanted reaction products or unexpected changes in the overall plasma properties due to the increased chemical complexity of the system. Increasing the CF4 fraction produces more F atoms for chemical etching as expected, but also more prominently lowers the density of Cl atoms, resulting in an actual drop in the etch rate under certain conditions. Furthermore, CF4 decreases the free electron density when mixed with Cl2. However, depending on the other gas components, CF4 gas can also sometimes enhance free electron density. This is the case when HBr is added to the mixture. The addition of H2 to the gas mixture will lower the sputtering process, not only due to the lower overall positive ion density at higher H2 fractions, but also because more H+, \\text{H}2+ and \\text{H}3+ are present and they have very low sputter yields. In contrast, a larger Cl2 fraction results in more chemical etching but also in less physical sputtering due to a smaller abundance of positive ions. Increasing the O2 fraction in the plasma will always lower the etch rate due to more oxidation of the wafer surface and due to a lower plasma density. However, it is also observed that the density of F atoms can actually increase with rising O2 gas fraction. This is relevant to note because the exact balance between fluorination and oxidation is

  12. H2S-Modified Fe-Ti Spinel: A Recyclable Magnetic Sorbent for Recovering Gaseous Elemental Mercury from Flue Gas as a Co-Benefit of Wet Electrostatic Precipitators.

    PubMed

    Zou, Sijie; Liao, Yong; Xiong, Shangchao; Huang, Nan; Geng, Yang; Yang, Shijian

    2017-03-21

    The nonrecyclability of the sorbents used to capture Hg(0) from flue gas causes a high operation cost and the potential risk of exposure to Hg. The installation of wet electrostatic precipitators (WESPs) in coal-fired plants makes possible the recovery of spent sorbents for recycling and the centralized control of Hg pollution. In this work, a H2S-modified Fe-Ti spinel was developed as a recyclable magnetic sorbent to recover Hg(0) from flue gas as a co-benefit of the WESP. Although the Fe-Ti spinel exhibited poor Hg(0) capture activity in the temperature range of flue gas downstream of flue gas desulfurization, the H2S-modified Fe-Ti spinel exhibited excellent Hg(0) capture performance with an average adsorption rate of 1.92 μg g(-1) min(-1) at 60 °C and a capacity of 0.69 mg g(-1) (5% of the breakthrough threshold) due to the presence of S2(2-) on its surface. The five cycles of Hg(0) capture, Hg(0) recovery, and sorbent regeneration demonstrated that the ability of the modified Fe-Ti spinel to capture Hg(0) did not degrade remarkably. Meanwhile, the ultralow concentration of Hg(0) in flue gas was increased to a high concentration of Hg(0), which facilitated the centralized control of Hg pollution.

  13. Process for the separation of components from gas mixtures

    DOEpatents

    Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

    1973-10-01

    A process for the removal, from gaseous mixtures of a desired component selected from oxygen, iodine, methyl iodide, and lower oxides of carbon, nitrogen, and sulfur is described. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatmospheric pressure to preferentially absorb the desired component in the fluorocarbon. Unabsorbed constituents of the gaseous mixture are withdrawn from the absorption zone. Liquid fluorocarbon enriched in the desired component is withdrawn separately from the zone, following which the desired component is recovered from the fluorocarbon absorbent. (Official Gazette)

  14. Separation of gases through gas enrichment membrane composites

    DOEpatents

    Swedo, Raymond J.; Kurek, Paul R.

    1988-01-01

    Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

  15. Separation of gases through gas enrichment membrane composites

    DOEpatents

    Swedo, R.J.; Kurek, P.R.

    1988-07-19

    Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

  16. Potential Flue Gas Impurities in Carbon Dioxide Streams Separated from Coal-fired Power Plants

    EPA Science Inventory

    For geological sequestration of CO2 separated from pulverized coal combustion flue gas, it is necessary to adequately evaluate the potential impacts of flue gas impurities on groundwater aquifers in the case of the CO2 leakage from its storage sites. This s...

  17. Central 300 PC of the Galaxy Probed by the Infrared Spectra of H_3^+ and Co: I. Predominance of Warm and Diffuse Gas and High H_2 Ionization Rate

    NASA Astrophysics Data System (ADS)

    Oka, Takeshi; Geballe, Thomas R.; Goto, Miwa; Usuda, Tomonori; Indriolo, Nick

    2016-06-01

    A low-resolution 2.0-2.5 μm survey of ˜500 very red point-like objects in the Central Molecular Zone (CMZ) of our Galaxy, initiated in 2008, has revealed many new bright objects with featureless spectra that are suitable for high resolution absorption spectroscopy of H_3^+ and CO. We now have altogether 48 objects mostly close to the Galactic plane located from 142 pc to the west of Sgr A* to 120 pc east allowing us to probe dense and diffuse gas by H_3^+ and dense gas by CO. Our observations demonstrate that the warm (˜250 K) and diffuse (≤100 cm-3) gas with a large column length (≥30 pc) initially observed toward the brightest star in the CMZ, GCS3-2 of the Quintuplet Cluster, exists throughout the CMZ with the surface filling factor of ˜ 100% dominating the region. The column densities of CO in the CMZ are found to be much less than those in the three foreground spiral arms except in the directions of Sgr B and Sgr E complexes and indicate that the volume filling factor of dense clouds of 10% previously estimated is a gross overestimate for the front half of the CMZ. Nevertheless the predominance of the newly found diffuse molecular gas makes the term "Central Molecular Zone" even more appropriate. The ultra-hot X-rays emitting plasma which some thought to dominate the region must be non existent except near the stars and SNRs. Recently the H_2 fraction f(H_2) in diffuse gas of the CMZ has been reported to be ˜0.6. If we use this value, the cosmic ray H_2 ionization rate ζ of a few times 10-15 s-1 reported earlier^b on the assumption of f(H_2)=1 needs to be increased by a factor of ˜3 since the value is approximately inversely proportional to f(H_2)^2. Geballe, T. R., Oka, T., Lambridges, E., Yeh, S. C. C., Schlegelmilch, B., Goto, M., Westrick, C. W., WI07 at the 70th ISMS, Urbana, IL, USA,2015 Oka, T., Geballe, T. R., Goto, M., Usuda, T., McCall, B. J. 2005, ApJ, 632, 882 Le Petit, F., Ruaud, M., Bron, E., Godard, B., Roueff, E., Languignon, D., Le

  18. Potential flue gas impurities in carbon dioxide streams separated from coal-fired power plants.

    PubMed

    Lee, Joo-Youp; Keener, Tim C; Yang, Y Jeffery

    2009-06-01

    For geological sequestration of carbon dioxide (CO2) separated from pulverized coal combustion flue gas, it is necessary to adequately evaluate the potential impacts of flue gas impurities on groundwater aquifers in the case of the CO2 leakage from its storage sites. This study estimated the flue gas impurities to be included in the CO2 stream separated from a CO2 control unit for a different combination of air pollution control devices and different flue gas compositions. Specifically, the levels of acid gases and mercury vapor were estimated for the monoethanolamine (MEA)-based absorption process on the basis of published performance parameters of existing systems. Among the flue gas constituents considered, sulfur dioxide (SO2) is known to have the most adverse impact on MEA absorption. When a flue gas contains 3000 parts per million by volume (ppmv) SO2 and a wet flue gas desulfurization system achieves its 95% removal, approximately 2400 parts per million by weight (ppmw) SO2 could be included in the separated CO2 stream. In addition, the estimated concentration level was reduced to as low as 135 ppmw for the SO2 of less than 10 ppmv in the flue gas entering the MEA unit. Furthermore, heat-stable salt formation could further reduce the SO2 concentration below 40 ppmw in the separated CO2 stream. In this study, it is realized that the formation rates of heat-stable salts in MEA solution are not readily available in the literature and are critical to estimating the levels and compositions of flue gas impurities in sequestered CO2 streams. In addition to SO2, mercury, and other impurities in separated CO2 streams could vary depending on pollutant removal at the power plants and impose potential impacts on groundwater. Such a variation and related process control in the upstream management of carbon separation have implications for groundwater protection at carbon sequestration sites and warrant necessary considerations in overall sequestration planning

  19. Influence of electrode separation and gas curtain on extreme ultraviolet emission of a gas jet z-pinch source

    NASA Astrophysics Data System (ADS)

    Mohanty, S. R.; Sakamoto, T.; Kobayashi, Y.; Izuka, N.; Kishi, N.; Song, I.; Watanabe, M.; Kawamura, T.; Okino, A.; Horioka, K.; Hotta, E.

    2006-07-01

    Extreme ultraviolet (EUV) emission from a gas jet z-pinch source has been examined by employing a photodiode and pinhole camera. Visible images of the pinched plasma have been also recorded. A current pulse of 10kA is used to heat the gas jet, which emits radiation around 13.5nm. Experimental parameters such as electrode separation and gas flow rate are varied to optimize EUV emission. The maximum EUV energy is obtained for 12mm electrode separation and 20Torr xenon pressure and it is estimated to 10.95mJ/sr per 2% bandwidth per pulse. The presence of gas curtain improves EUV emission by 30%.

  20. Line strength and collisional broadening coefficients of H2O at 2.7 μm for natural gas quality assurance applications

    NASA Astrophysics Data System (ADS)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker

    2014-09-01

    We employed tunable diode laser absorption spectroscopy to measure the line strength, the methane (CH4), ethane (C2H6) and the propane (C3H8) broadening coefficients for the 523-422 H2O transition at 3619.61 cm-1. Water amount fractions generated by a stable and accurate humidity transfer standard, traceable to the SI units via the German national humidity standard, were used to calibrate the spectroscopic line strength measurements. We focus on the traceability of the measured line data to the SI and on uncertainty assessments following the guidelines of the Guide to the Expression of Uncertainty in Measurement. We determined the line strength to be (8.42 ± 0.07)×10-20 cm-1/(cm-2 molecule) corresponding to a relative uncertainty of ±0.8%. To the best of our knowledge, we report the first methane, ethane and propane broadening coefficients of (8.037 ± 0.056)×10-5 cm-1/hPa, (9.077 ± 0.064)×10-5 cm-1/hPa and (10.469 ± 0.073)×10-5 cm-1/hPa for the 523-422 H2O transition at 3619.61 cm-1, respectively. The relative combined uncertainties of the stated CH4, C2H6 and C3H8 broadening coefficients are in the ±0.7% range.

  1. AC plasma torch with a H2O/CO2/CH4 mix as the working gas for methane reforming

    NASA Astrophysics Data System (ADS)

    Rutberg, Ph G.; Nakonechny, Gh V.; Pavlov, A. V.; Popov, S. D.; Serba, E. O.; Surov, A. V.

    2015-06-01

    This paper presents results of investigations implemented during construction of the three-phase ac plasma torch working on a mixture of steam with carbon dioxide and methane (H2O/CO2/CH4) with power upto 120 kW. Such thermal plasma generators are needed in industrial technologies for methane reforming with the aim of producing the syngas comprising of the hydrogen and carbon mono-oxide (H2/CO). It was shown that during plasma torch work there are two character parts of the high-voltage arc. In these parts, the arc column has a different diameter and temperature about (8.5  -  8.3) · 103 K and (10.5  -  10.0) · 103 K, respectively. The plasma torch output characteristics have been obtained for working regimes with various flow rates of the methane (0.0-0.8 g s-1) in the plasma-forming mix and constant flow rates of the carbon dioxide and water steam (each of 3.0 g s-1). For the mentioned mix of gases, the unit generates plasma with the mass-average temperature ~(3.2-3.3) · 103K and the thermal efficiency ~94-96%. This provides effective reforming of methane.

  2. Performance enhancement of open loop gas recovery process by centrifugal separation of gases

    NASA Astrophysics Data System (ADS)

    Kalmani, S. D.; Joshi, A. V.; Bhattacharya, S.; Hunagund, P. V.

    2016-11-01

    The proposed INO-ICAL detector [1] is going to be instrumented with 28800 RPCs (Resistive Plate Chamber). These RPCs (2 × 2 m2 size) will consist of two glass electrodes separated by 2 mm and will use a gas mixture of Freon R134a, isobutane and sulphur hexafluoride (in the ratio of 95.3:4.5:0.2). An Open Ended System (OES), in which the gas mixture is vented to the atmosphere after a single passage through the detector, is most commonly used for small detector setups. However, OES cannot be used with the INO-ICAL detector due to reasons of cost and pollution. It is necessary, therefore, to recirculate the gas mixture in a closed loop. In a Closed Loop gas System (CLS) [2] the gas mixture is purified and recirculated after flowing through the RPC. The impurities which get accumulated in the gas mixture due to leaks or formation of radicals are removed by suitable filters. The Open Loop System (OLS) [3] is based on the separation and recovery of major gas components after passage of the gas mixture through the RPCs. and has the advantage that it does not need filters for removal of impurities. However a CLS is found to be more efficient than OLS in the recovery of gases in the mixture. In this paper we discuss centrifugal separation [4] as a technique to extract major gas constituents and use this technique to improve the efficiency of OLS. Results from preliminary trial runs are reported.

  3. Doping and defect structure of mixed-conducting ceramics for gas separation

    NASA Astrophysics Data System (ADS)

    Zuo, Chendong

    A worldwide energy crisis and increasing environmental concerns are strong incentives for using hydrogen as a sustainable and clean energy source. "Hydrogen economy" has been around since 1970s, but it started to look practicable only in recent years. The trend in the future is to switch from using hydrogen as the basic raw material in the chemical industry to the energy carrier in the transportation and distributed energy industries. To meet the expected rising demand, hydrogen has to be generated in a more cost-effective manner. As one of the most important operation units in the hydrogen production, a high performance hydrogen separation membrane system is essential to the coming hydrogen economy. The project of hydrogen separation membrane based on Mixed ionic and electronic conductor (MIEC) composite was initiated by DoE years ago, and the MIEC membrane has been developed in Argonne National Laboratory (ANL) for several years. The goal at ANL is to develop a dense, ceramic-based MIEC membrane that is highly selective, chemical stable in practical environments at operative temperatures up to ≈900°C, and can separate hydrogen from mixed gases at commercially significant fluxes under industrially relevant operating conditions, without the need for electrodes or electrical circuitry. The effort at ANL initially focused on BCY20 (BaCe0.8Y 0.2O3). BCY20 forms the matrix of ANL-1a and -2a ceramic-metal composite membranes (40-50 vol.% of a metal is dispersed in a ceramic matrix) and its bulk transport properties, including ionic transfer number, ionic and electronic conductivity, and chemical and mechanical stability have been systematically studied. However, exposure to CO2 and H2O-containing atmospheres, as would be present in a practical environment, will degrade the material as it reacts to form insulating barium carbonate (BaCO3 ) and cerium oxide (CeO2). This decomposition greatly limits its applicability in hydrogen separation, despite the promising

  4. Molecular Dynamics Studies of Surface Difference Effect on Gas Separation by Zeolite Membranes

    NASA Astrophysics Data System (ADS)

    Mizukami, Koichi; Kobayashi, Yasunori; Morito, Hideaki; Takami, Seiichi; Kubo, Momoji; Belosludov, Rodion; Miyamoto, Akira

    2000-07-01

    The permeation of CO2/N2 gas mixture through zeolite membranes was investigated by molecular dynamics (MD) study. MD calculation successfully reproduced the experimental results of CO2/N2 separation by NaY membrane. Furthermore, the surface difference effect on gas separation was examined using the NaA zeolite (100) surface and its (111) surface. The CO2/N2 separation factor of the (111) surface was much lower than that of the (100) surface. This was caused by the difference in surface structure, since the pore structures of both models were the same.

  5. Preparation and characterization of composite membrane for high temperature gas separation

    SciTech Connect

    Ilias, S.; King, F.G.; Su, N.

    1994-10-01

    The objective of this project is to develop thin film palladium membranes for separation of hydrogen in high temperature applications. The authors plan to use electroless plating to deposit thin palladium films on microporous ceramic and silver substrates and then characterize the membrane in terms of permeability and selectivity for gas separation. To accomplish the research objective, the project requires three tasks: Development of a process for composite membrane fabrication; Characterization of composite membrane; and Development of theoretical model for hydrogen gas separation. The experimental procedures are described.

  6. Membrane loop process for separating carbon dioxide for use in gaseous form from flue gas

    SciTech Connect

    Wijmans, Johannes G; Baker, Richard W; Merkel, Timothy C

    2014-10-07

    The invention is a process involving membrane-based gas separation for separating and recovering carbon dioxide emissions from combustion processes in partially concentrated form, and then transporting the carbon dioxide and using or storing it in a confined manner without concentrating it to high purity. The process of the invention involves building up the concentration of carbon dioxide in a gas flow loop between the combustion step and a membrane separation step. A portion of the carbon dioxide-enriched gas can then be withdrawn from this loop and transported, without the need to liquefy the gas or otherwise create a high-purity stream, to a destination where it is used or confined, preferably in an environmentally benign manner.

  7. Membrane loop process for separating carbon dioxide for use in gaseous form from flue gas

    SciTech Connect

    Wijmans, Johannes G; Baker, Richard W; Merkel, Timothy C

    2016-09-06

    The invention is a process involving membrane-based gas separation for separating and recovering carbon dioxide emissions from combustion processes in partially concentrated form, and then transporting the carbon dioxide and using or storing it in a confined manner without concentrating it to high purity. The process of the invention involves building up the concentration of carbon dioxide in a gas flow loop between the combustion step and a membrane separation step. A portion of the carbon dioxide-enriched gas can then be withdrawn from this loop and transported, without the need to liquefy the gas or otherwise create a high-purity stream, to a destination where it is used or confined, preferably in an environmentally benign manner.

  8. Electrochemical performance of lithium-sulfur batteries based on a sulfur cathode obtained by H2S gas treatment of a lithium salt

    NASA Astrophysics Data System (ADS)

    Dressel, Carina B.; Jha, Himendra; Eberle, Anna-Marietta; Gasteiger, Hubert A.; Fässler, Thomas F.

    2016-03-01

    A new technique to produce Li2S/C composites and Li2S cathodes as well as their application in high-capacity Li-S batteries is demonstrated. The simple but effective method converts an easy-to-handle lithium salt-containing composite or electrode to Li2S using H2S. The main advantage is that the conversion to Li2S can be performed towards the final stage of the electrode preparation process, which significantly reduces the need of controlled atmosphere otherwise required for Li2S handling. LiOH is used to demonstrate the technique, and such fabricated Li2S electrode is successfully used in a Li-S battery (half-cell) where it shows discharge capacities of up to 770 mAh g-1(Li2S) and retained >410 mAh g-1(Li2S) after 100 cycles at C/5.

  9. Evaluation of Electrochemical Nitrogen/hydrogen Gas Separator

    NASA Technical Reports Server (NTRS)

    Clifford, J. E.; Sexton, R. W.

    1973-01-01

    An electrochemical nitrogen-hydrogen separator subsystem was investigated for use following catalytic dissociation of ammonia or hydrazine in a storage system being considered for long-duration manned space flight. An experimental cell with concentric tubular Pd-25Ag alloy hydrogen diffusion electrodes and hermetically sealed aqueous caustic electrolyte was developed.It was found that this cell operated satisfactorily at 210 C to 245 C and produced dry nitrogen and dry hydrogen with either or both gases at pressures up to 6.8 atmospheres (100 psia) or higher for storage. The final cell developed was operated satisfactorily for 176 days (4200 hours) with no evidence of deterioration of current-voltage performance. The best experimental performance was obtained at 245 C at currents up to 4 amperes (180 ma/sq cm and 360 ma/sq cm anode and cathode current densities, respectively) with a maximum steady-state cell voltage of 0.125 volt for an anode feed of pure hydrogen.

  10. Process and apparatus for separation of components of a gas stream

    DOEpatents

    Bryan, Charles R; Torczynski, John R; Brady, Patrick V; Gallis, Michail; Brooks, Carlton F

    2013-09-17

    A process and apparatus for separating a gas mixture comprising providing a slot in a gas separation channel (conceptualized as a laterally elongated Clusius-Dickel column), having a length through which a net cross-flow of the gas mixture may be established; applying a higher temperature to one side of the channel and a lower temperature on an opposite side of the channel thereby causing thermal-diffusion and buoyant-convection flow to occur in the slot; and establishing a net cross-flow of a gas mixture comprising at least one higher density gas component and at least one lower density gas component along the length of the slot, wherein the cross-flow causes, in combination with the convection flow, a spiraling flow in the slot; and wherein the spiral flow causes an increasing amount of separation of the higher density gas from the lower density gas along the length of the channel. The process may use one or more slots and/or channels.

  11. Process and apparatus for separation of components of a gas stream

    DOEpatents

    Bryan, Charles R.; Torczynski, John R.; Brady, Patrick V.; Gallis, Michail; Brooks, Carlton F.

    2014-06-17

    A process and apparatus for separating a gas mixture comprising providing a slot in a gas separation channel (conceptualized as a laterally elongated Clusius-Dickel column), having a length through which a net cross-flow of the gas mixture may be established; applying a higher temperature to one side of the channel and a lower temperature on an opposite side of the channel thereby causing thermal-diffusion and buoyant-convection flow to occur in the slot; and establishing a net cross-flow of a gas mixture comprising at least one higher density gas component and at least one lower density gas component along the length of the slot, wherein the cross-flow causes, in combination with the convection flow, a spiraling flow in the slot; and wherein the spiral flow causes an increasing amount of separation of the higher density gas from the lower density gas along the length of the channel. The process may use one or more slots and/or channels.

  12. Process and apparatus for separation of components of a gas stream

    DOEpatents

    Bryan, Charles R; Torczynski, John R; Brady, Patrick V; Gallis, Michail; Brooks, Carlton F

    2013-11-19

    A process and apparatus for separating a gas mixture comprising providing a slot in a gas separation channel (conceptualized as a laterally elongated Clusius-Dickel column), having a length through which a net cross-flow of the gas mixture may be established; applying a higher temperature to one side of the channel and a lower temperature on an opposite side of the channel thereby causing thermal-diffusion and buoyant-convection flow to occur in the slot; and establishing a net cross-flow of a gas mixture comprising at least one higher density gas component and at least one lower density gas component along the length of the slot, wherein the cross-flow causes, in combination with the convection flow, a spiraling flow in the slot; and wherein the spiral flow causes an increasing amount of separation of the higher density gas from the lower density gas along the length of the channel. The process may use one or more slots and/or channels.

  13. Effectiveness and reaction networks of H2O2 vapor with NH3 gas for decontamination of the toxic warfare nerve agent, VX on a solid surface.

    PubMed

    Gon Ryu, Sam; Wan Lee, Hae

    2015-01-01

    The nerve agent, O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) must be promptly eliminated following its release into the environment because it is extremely toxic, can cause death within a few minutes after exposure, acts through direct skin contact as well as inhalation, and persists in the environment for several weeks after release. A mixture of hydrogen peroxide vapor and ammonia gas was examined as a decontaminant for the removal of VX on solid surfaces at ambient temperature, and the reaction products were analyzed by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectrometry (NMR). All the VX on glass wool filter disks was found to be eliminated after 2 h of exposure to the decontaminant mixtures, and the primary decomposition product was determined to be non-toxic ethyl methylphosphonic acid (EMPA); no toxic S-[2-(diisopropylamino)ethyl] methylphosphonothioic acid (EA-2192), which is usually produced in traditional basic hydrolysis systems, was found to be formed. However, other by-products, such as toxic O-ethyl S-vinyl methylphosphonothioate and (2-diisopropylaminoethyl) vinyl disulfide, were detected up to 150 min of exposure to the decontaminant mixture; these by-products disappeared after 3 h. The two detected vinyl byproducts were identified first in this study with the decontamination system of liquid VX on solid surfaces using a mixture of hydrogen peroxide vapor and ammonia gas. The detailed decontamination reaction networks of VX on solid surfaces produced by the mixture of hydrogen peroxide vapor and ammonia gas were suggested based on the reaction products. These findings suggest that the mixture of hydrogen peroxide vapor and ammonia gas investigated in this study is an efficient decontaminant mixture for the removal of VX on solid surfaces at ambient temperature despite the formation of a toxic by-product in the reaction process.

  14. Possible sources of H2 to H2O enrichment at evaporation of parent chondritic material

    NASA Technical Reports Server (NTRS)

    Makalkin, A. B.; Dorofeyeva, V. A.; Vityazev, A. V.

    1993-01-01

    One of the results obtained from thermodynamic simulation of recondensation of the source chondritic material is that at 1500-1800 K it's possible to form iron-rich olivine by reaction between enstatite, metallic iron and water vapor in the case of (H2O)/(H2) approximately equal to 0.1. This could be reached if the gas depletion in hydrogen is 200-300 times relative to solar abundance. To get this range of depletion one needs some source material more rich in hydrogen than the carbonaceous CI material which is the richest in volatiles among chondrites. In the case of recondensation at impact heating and evaporation of colliding planetesimals composed of CI material, we obtain insufficiently high value of (H2)/(H2O) ratio. In the present paper we consider some possible source materials and physical conditions necessary to reach gas composition with (H2)/(H2O) approximately 10 at high temperature.

  15. Improved high efficiency third stage separator cyclones for separation of fines from fluid catalytic cracking flue gas

    SciTech Connect

    Chitnis, G.K.; Schatz, K.W.; Bussey, B.K.

    1996-12-31

    Stairmand type small diameter (0.254 m) multicyclones were cold flow tested for fluid catalytic cracking third stage separator application. The gas discharge from the cyclone dust outlet into the common collection hopper was found to far exceed the hopper bleed rate (underflow). The excess gas reentrained dust from the hopper back into cyclones, which lowered collection efficiencies. Vortex {open_quotes}stabilization{close_quotes} using apex cones was unsuccessful whereas a Mobil proprietary cyclone modification was successful in minimizing excess gas discharge and dust reentrainment at the cyclone-hopper boundary. In tests at 700 {degrees}C, the modified cyclones captured all particles above 4 {mu}m. Mobil-Kellogg incorporated the modified cyclones in a new third stage separator design which is targeted for achieving lowest opacity and <50 mg/Nm{sup 3} emissions at the stack. The first such unit will be commercialized in Mobil`s newest catalytic cracker (M.W. Kellogg design) under construction in Altona, Australia in late 1996. 5 refs., 4 figs., 2 tabs.

  16. Fluid Phase Separation (FPS) experiment for flight on a space shuttle Get Away Special (GAS) canister

    NASA Technical Reports Server (NTRS)

    Peters, Bruce; Wingo, Dennis; Bower, Mark; Amborski, Robert; Blount, Laura; Daniel, Alan; Hagood, Bob; Handley, James; Hediger, Donald; Jimmerson, Lisa

    1990-01-01

    The separation of fluid phases in microgravity environments is of importance to environmental control and life support systems (ECLSS) and materials processing in space. A successful fluid phase separation experiment will demonstrate a proof of concept for the separation technique and add to the knowledge base of material behavior. The phase separation experiment will contain a premixed fluid which will be exposed to a microgravity environment. After the phase separation of the compound has occurred, small samples of each of the species will be taken for analysis on the Earth. By correlating the time of separation and the temperature history of the fluid, it will be possible to characterize the process. The experiment has been integrated into space available on a manifested Get Away Special (GAS) experiment, CONCAP 2, part of the Consortium for Materials Complex Autonomous Payload (CAP) Program, scheduled for STS-42. The design and the production of a fluid phase separation experiment for rapid implementation at low cost is presented.

  17. Gas separation process using membranes with permeate sweep to remove CO.sub.2 from gaseous fuel combustion exhaust

    DOEpatents

    Wijmans, Johannes G [Menlo Park, CA; Merkel, Timothy C [Menlo Park, CA; Baker, Richard W [Palo Alto, CA

    2012-05-15

    A gas separation process for treating exhaust gases from the combustion of gaseous fuels, and gaseous fuel combustion processes including such gas separation. The invention involves routing a first portion of the exhaust stream to a carbon dioxide capture step, while simultaneously flowing a second portion of the exhaust gas stream across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas back to the combustor.

  18. Device for two-dimensional gas-phase separation and characterization of ion mixtures

    DOEpatents

    Tang, Keqi; Shvartsburg, Alexandre A.; Smith, Richard D.

    2006-12-12

    The present invention relates to a device for separation and characterization of gas-phase ions. The device incorporates an ion source, a field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer, an ion mobility spectrometry (IMS) drift tube, and an ion detector. In one aspect of the invention, FAIMS operating voltages are electrically floated on top of the IMS drift voltage. In the other aspect, the FAIMS/IMS interface is implemented employing an electrodynamic ion funnel, including in particular an hourglass ion funnel. The present invention improves the efficiency (peak capacity) and sensitivity of gas-phase separations; the online FAIMS/IMS coupling creates a fundamentally novel two-dimensional gas-phase separation technology with high peak capacity, specificity, and exceptional throughput.

  19. Feasibility of the preparation of silica monoliths for gas chromatography: fast separation of light hydrocarbons.

    PubMed

    Azzouz, Imadeddine; Essoussi, Anouar; Fleury, Joachim; Haudebourg, Raphael; Thiebaut, Didier; Vial, Jerome

    2015-02-27

    The preparation conditions of silica monoliths for gas chromatography were investigated. Silica-based monolithic capillary columns based on sol-gel process were tested in the course of high-speed gas chromatographic separations of light hydrocarbons mixture (C1-C4). The impact of modifying the amount of porogen and/or catalyst on the monolith properties were studied. At the best precursor/catalyst/porogen ratio evaluated, a column efficiency of about 6500 theoretical plates per meter was reached with a very good resolution (4.3) for very light compounds (C1-C2). The test mixture was baseline separated on a 70cm column. To our knowledge for the first time a silica-based monolithic capillary column was able to separate light hydrocarbons from methane to n-butane at room temperature with a back pressure in the range of gas chromatography facilities (under 4.1bar).

  20. Capillary gas-liquid chromatography separation of phenethylamines in amphetamine-positive urine samples.

    PubMed

    DePace, A; Verebey, K; elSohly, M

    1990-11-01

    Good gas chromatography (GC) separation of molecules is essential for clean gas chromatography/mass spectrometry (GC/MS) confirmation of compounds. The trifluoro derivatives of ephedrine (E) and methamphetamine (MA) coelute on dimethyl silicone capillary columns, such as DB-1, which are most commonly used by chromatographers. Methods are described to separate E and MA to aid GC/MS confirmations of methamphetamine, ephedrine, or both E and MA together, whichever may be present in Enzyme Immunoassay (EIA)-analyzed amphetamine-positive urine samples. The use of the heptafluoro derivatives of E and MA on a DB-1 column, or the trifluoro derivatives of E and MA on a DB-17 column, is suggested for good gas chromatographic separation.

  1. Gas separation by the molecular exchange flow through micropores of the membrane

    NASA Astrophysics Data System (ADS)

    Matsumoto, Michiaki; Nakaye, Shoeji; Sugimoto, Hiroshi

    2016-11-01

    A model gas separator that makes use of the molecular exchange flow through porous membrane of 18 cm2 area is fabricated. The gas separator performance is tested for helium-neon mixture. The separator divides a continuous flow of gas mixture into two flows of different gases. The difference of mole percentage is around 8 % at the volumetric feed flow rate of 1 sccm. In the present system, the molecular exchange flow is induced in two Knudsen pumps, where the mixed cellulose ester membrane is used as the thermal transpiration material. The experiment demonstrates the capability of these pumps to increase the concentration of heavy and light molecules, respectively, from the feed mixture.

  2. Potential flue gas impurities in carbon dioxide streams separated from coal-fired power plants

    SciTech Connect

    Joo-Youp Lee; Tim C. Keener; Y. Jeffery Yang

    2009-06-15

    This study estimated the flue gas impurities to be included in the CO{sub 2} stream separated from a CO{sub 2} control unit for a different combination of air pollution control devices and different flue gas compositions. Specifically, the levels of acid gases and mercury vapor were estimated for the monoethanolamine (MEA)-based absorption process on the basis of published performance parameters of existing systems. Among the flue gas constituents considered, sulfur dioxide (SO{sub 2}) is known to have the most adverse impact on MEA absorption. When a flue gas contains 3000 parts per million by volume (ppmv) SO{sub 2} and a wet flue gas desulfurization system achieves its 95% removal, approximately 2400 parts per million by weight (ppmw) SO{sub 2} could be included in the separated CO{sub 2} stream. In addition, the estimated concentration level was reduced to as low as 135 ppmw for the SO{sub 2} of less than 10 ppmv in the flue gas entering the MEA unit. Furthermore, heat-stable salt formation could further reduce the SO{sub 2} concentration below 40 ppmw in the separated CO{sub 2} stream. In this study, it is realized that the formation rates of heat-stable salts in MEA solution are not readily available in the literature and are critical to estimating the levels and compositions of flue gas impurities in sequestered CO{sub 2} streams. In addition to SO{sub 2}, mercury, and other impurities in separated CO{sub 2} streams could vary depending on pollutant removal at the power plants and impose potential impacts on groundwater. Such a variation and related process control in the upstream management of carbon separation have implications for groundwater protection at carbon sequestration sites and warrant necessary considerations in overall sequestration planning, engineering, and management. 63 refs., 1 fig., 3 tabs.

  3. Reactivity of CO2 and H2O on TiO2 catalysts studied by gas phase FT-IR method and deactivation mechanism

    NASA Astrophysics Data System (ADS)

    Maruo, Y. Y.; Yamada, T.; Tsuda, M.

    2012-08-01

    The photoreduction of CO2 to hydrocarbons is a sustainable energy technology that not only reduces emissions but also the need for alternative fuels. Wide band-gap TiO2 catalysts are considered the most convenient candidates in terms of cost and stability. In this work, anatase TiO2 powder was deposited on a silica filter paper, and photoreduction experiments were carried out in an FT-IR gas reactor using CO2 gas with 50% relative humidity as the reactant under the irradiation of a high pressure Hg lamp. CH4 and CO were detected as the CO2 reduction products. However, there was a gradual decrease in the amounts of CH4 and CO that were produced, seemingly because of the deactivation of the anatase TiO2 surface. We analyzed the surface chemical states using XPS analysis to consider the cause of the TiO2 deactivation, and found that the amounts of -OH group had increased on the TiO2 surface after Hg lamp irradiation. Considering the analysis results, we assumed a surface deactivation mechanism.

  4. Gas separation in a membrane unit: Experimental results and theoretical predictions

    SciTech Connect

    Tranchino, L.; Santarossa, R.; Carta, F. ); Fabiani, C.; Bimbi, L. )

    1989-11-01

    A laboratory membrane separation unit was assembled by using composite hollow fibers. It was tested in an automated apparatus for gas separation measurements. The performances of the system were measured for CH{sub 4}/CO{sub 2} mixtures as functions of temperature, pressure, stage cut, feed gas composition, and flow regime. The results were analyzed on the basis of a predictive mathematical model of the process. A good fitting of the data was obtained in most cases except at high pressure, probably as a consequence of structural changes of the active layer of the fibers under pressurization.

  5. Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

    SciTech Connect

    Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W.; Zhang, M. M.; Xu, D.

    2014-01-29

    In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

  6. Effect of evaporation time on cellulose acetate membrane for gas separation

    NASA Astrophysics Data System (ADS)

    Jami'an, W. N. R.; Hasbullah, H.; Mohamed, F.; Yusof, N.; Ibrahim, N.; Ali, R. R.

    2016-06-01

    Throughout this decades, membrane technology has been the desirable option among the others gas separation technologies. However, few issues have been raised regarding the membrane gas separation application including the trade-off between its permeability and selectivity and also its effects towards environment. Therefore, for this research, a biopolymer membrane for gas separation application will be developed with reasonably high on both permeability and selectivity. The main objective of this research is to study the effect of solvent evaporation time on the flat sheet asymmetric membrane morphology and gas separation performance. The membranes were produced by a simple dry/wet phase inversion technique using a pneumatically controlled casting system. The dope solution for the membrane casting was prepared by dissolving the cellulose acetate (CA) polymer in N-Methyl-2-pyrrolidone (NMP) and the solvent evaporation time was varied. Permeability and selectivity of the membrane was performed by using pure gases of carbon dioxide, CO2 and methane, CH4. The increase in solvent evaporation time had improved the membrane morphologies as the porosity of the membrane surface decrease and formation of a more mature skin layer. The gas permeation tests determined that increasing in solvent evaporation time had increased the selectivity of CO2/CH4 but reduce the permeability of both gases

  7. Separation techniques: membranes for natural gas sweetening and CO/sub 2/ enrichment

    SciTech Connect

    Mazur, W.H.; Chan, M.C.

    1982-10-01

    The ability of polymeric membranes to separate gases has been poor since the 19th century. Early polymeric membranes showed poor selectivity (separation); even the most permeable of gases exhibited poor productivities (fluxes). Due to the inability to perfect a process to produce uniformly good membranes in quantity, practical industrial gas separation systems were not successful. In 1960, a technical breakthrough came with the development of asymmetric membranes for reverse osmosis and their subsequent adaptation to gaseous separation. Based upon development and commercialization of membranes for water desalination by reverse osmosis, Envirogenics Systems Co. has developed gas separation membranes suitable for large-scale industrial applications. The cellulose acetate membrane is produced in flat sheet form and to retain its asymmetric character the membrane is heat-treated and dried by proprietary techniques. This produces a highly selective, dense, active layer with a thick porous support layer having high mechanical stability to withstand high feed gas pressures and high pressure differentials. The membrane is incorporated into spiral-wound elements similar to those for reverse osmosis applications. The membrane, which has been field tested for sweetening natural gas, also can be used for enhanced oil recovery and oxygen enrichment.

  8. Estimated CO2, SO2 and H2S emission to the atmosphere from the 2011 El Hierro submarine eruption (Canary Islands) on the basis of helicopter gas surveys

    NASA Astrophysics Data System (ADS)

    Barrancos, J.; Padilla, G.; Padrón, E.; Hernández, P. A.; Calvo, D.; Marquez, A.; Pérez, N. M.; Melian, G.; Dionis, S.; Rodríguez, F.; Nolasco, D.; Hernández, I.

    2012-04-01

    An accurate estimation of SO2 emission rates is an important issue to elucidate the activity of volcanoes, moreover the monitoring of its temporal evolution might help to predict a possible eruption and thus, save the loss of human's lives in cities nearby volcanoes. In the lasts years new instruments have been developed and improved, in order to be more portable, cheaper and lighter. The miniDOAS consist of a small spectrometer with a lens for collecting scattered UV light, and are controlled/powered via USB with a laptop. Recently, new technical developments have allowed monitoring the emission of other gas species such as CO2, H2S, etc from volcanic plumes by means of portable multisensor system. With both devices we were able to evaluate the SO2 emission rates and the molar ratios of major volcanic gas components, respectively. Multiplying the observed SO2 emission rate times the observed (gas)i/SO2 mass ratios (CO2/SO2 and H2S/SO2) allowed us to estimate other volatiles emission rates. Between November 11, 2011, and January 16, 2012, and as a consequence of the submarine volcanic eruption started on October 10, 2011, south off shore El Hierro, Canary Islands, a regularly monitoring of the volcanic plume from the submarine volcano has been performed with remote sensors, always depending of helicopter availability. The instruments are mounted aboard on a helicopter belonged to the Helicopter Unit of Spanish Civil Guard. The SO2 flux measured during this period showed a maximum SO2 emission of 109 ± 19 t/d on November 6, just two days before the occurrence of a intense bubbling at the sea surface on November 8, producing a water, gas and ash column of about 15 meters over the sea surface. That day, CO2 and H2S emission also reached the maximum measured, with 5400 t/d and 3.6 t/d, respectively. Since then, SO2, CO2 and H2S emission rates have declined to values close to detection limit (~ 2 t/d for SO2). These results report the first SO2 emission rates measured

  9. Ecosystem CO2/H2O fluxes are explained by hydraulically limited gas exchange during tree mortality from spruce bark beetles

    NASA Astrophysics Data System (ADS)

    Frank, John M.; Massman, William J.; Ewers, Brent E.; Huckaby, Laurie S.; Negrón, José F.

    2014-06-01

    Disturbances are increasing globally due to anthropogenic changes in land use and climate. This study determines whether a disturbance that affects the physiology of individual trees can be used to predict the response of the ecosystem by weighing two competing hypothesis at annual time scales: (a) changes in ecosystem fluxes are proportional to observable patterns of mortality or (b) to explain ecosystem fluxes the physiology of dying trees must also be incorporated. We evaluate these hypotheses by analyzing 6 years of eddy covariance flux data collected throughout the progression of a spruce beetle (Dendroctonus rufipennis) epidemic in a Wyoming Engelmann spruce (Picea engelmannii)-subalpine fir (Abies lasiocarpa) forest and testing for changes in canopy conductance (gc), evapotranspiration (ET), and net ecosystem exchange (NEE) of CO2. We predict from these hypotheses that (a) gc, ET, and NEE all diminish (decrease in absolute magnitude) as trees die or (b) that (1) gc and ET decline as trees are attacked (hydraulic failure from beetle-associated blue-stain fungi) and (2) NEE diminishes both as trees are attacked (restricted gas exchange) and when they die. Ecosystem fluxes declined as the outbreak progressed and the epidemic was best described as two phases: (I) hydraulic failure caused restricted gc, ET (28 ± 4% decline, Bayesian posterior mean ± standard deviation), and gas exchange (NEE diminished 13 ± 6%) and (II) trees died (NEE diminished 51 ± 3% with minimal further change in ET to 36 ± 4%). These results support hypothesis b and suggest that model predictions of ecosystem fluxes following massive disturbances must be modified to account for changes in tree physiological controls and not simply observed mortality.

  10. Analysis of CO2 Separation from Flue Gas, Pipeline Transportation, and Sequestration in Coal

    SciTech Connect

    Eric P. Robertson

    2007-09-01

    This report was written to satisfy a milestone of the Enhanced Coal Bed Methane Recovery and CO2 Sequestration task of the Big Sky Carbon Sequestration project. The report begins to assess the costs associated with separating the CO2 from flue gas and then injecting it into an unminable coal seam. The technical challenges and costs associated with CO2 separation from flue gas and transportation of the separated CO2 from the point source to an appropriate sequestration target was analyzed. The report includes the selection of a specific coal-fired power plant for the application of CO2 separation technology. An appropriate CO2 separation technology was identified from existing commercial technologies. The report also includes a process design for the chosen technology tailored to the selected power plant that used to obtain accurate costs of separating the CO2 from the flue gas. In addition, an analysis of the costs for compression and transportation of the CO2 from the point-source to an appropriate coal bed sequestration site was included in the report.

  11. Efficient gas-separation process to upgrade dilute methane stream for use as fuel

    DOEpatents

    Wijmans, Johannes G [Menlo Park, CA; Merkel, Timothy C [Menlo Park, CA; Lin, Haiqing [Mountain View, CA; Thompson, Scott [Brecksville, OH; Daniels, Ramin [San Jose, CA

    2012-03-06

    A membrane-based gas separation process for treating gas streams that contain methane in low concentrations. The invention involves flowing the stream to be treated across the feed side of a membrane and flowing a sweep gas stream, usually air, across the permeate side. Carbon dioxide permeates the membrane preferentially and is picked up in the sweep air stream on the permeate side; oxygen permeates in the other direction and is picked up in the methane-containing stream. The resulting residue stream is enriched in methane as well as oxygen and has an EMC value enabling it to be either flared or combusted by mixing with ordinary air.

  12. Membrane gas separation. (Latest citations from the NTIS data base). Published Search

    SciTech Connect

    Not Available

    1992-08-01

    The bibliography contains citations concerning the research and development of gas separation and purification techniques involving the use of plastic and metal membranes. Among the topics included are isotope separation, osmotic techniques, reverse osmosis, and preparation of membranes for specific separation processes. The permeability of polymer membranes is discussed in terms of physical properties as well as molecular structure. The selectivity of polymeric films for a variety of gases is also included. (Contains a minimum of 168 citations and includes a subject term index and title list.)

  13. Membrane gas separation. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1993-08-01

    The bibliography contains citations concerning the research and development of gas separation and purification techniques involving the use of plastic and metal membranes. Citations review isotope separation, osmotic techniques, reverse osmosis, and preparation of membranes for specific separation processes. The permeability of polymer membranes is discussed in terms of physical properties as well as molecular structure. The selectivity of polymeric films for a variety of gases is also included. (Contains a minimum of 198 citations and includes a subject term index and title list.)

  14. Membrane gas separation. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-01-01

    The bibliography contains citations concerning the research and development of gas separation and purification techniques involving the use of plastic and metal membranes. Citations review isotope separation, osmotic techniques, reverse osmosis, and preparation of membranes for specific separation processes. The permeability of polymer membranes is discussed in terms of physical properties as well as molecular structure. The selectivity of polymeric films for a variety of gases is also included. (Contains a minimum of 205 citations and includes a subject term index and title list.)

  15. Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 2; Gas Separation Technology--State of the Art

    NASA Technical Reports Server (NTRS)

    Reynolds, Thomas L.; Eklund, Thor I.; Haack, Gregory A.

    2001-01-01

    This purpose of this contract study task was to investigate the State of the Art in Gas Separation Technologies utilized for separating air into both nitrogen and oxygen gases for potential applications on commercial aircraft. The intended applications included: nitrogen gas for fuel tank inerting, cargo compartment fire protection, and emergency oxygen for passenger and crew use in the event of loss of cabin pressure. The approach was to investigate three principle methods of gas separation: Hollow Fiber Membrane (HFM), Ceramic Membrane (CM), and liquefaction: Total Atmospheric Liquefaction of Oxygen and Nitrogen (TALON). Additional data on the performance of molecular sieve pressure swing adsorption (PSA) systems was also collected and discussed. Performance comparisons of these technologies are contained in the body of the report.

  16. Effect of H2S and COS in the fuel gas on the performance of ambient pressure phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Ross, P. N., Jr.

    1985-04-01

    The objective of this project was to determine in laboratory cells the tolerance of phosphoric acid fuel cells (PAFC) to hydrogen sulfide and carbonyl sulphide impurities in the anode feed gas. The study was conducted in three phases: the first was testing in a small (1 sq cm) free electrolyte cell to examine the effect of electrode structure on cell tolerance and to determine the order of magnitude of sulfur causing failure in cells at zero utilization; the second was testing in standard 2' x 2' PAFC laboratory hardware at ambient pressure to examine the effect of hydrogen utilization on tolerance and the possible effect of fuel impurities on cathode performance; the final phase was testing with a 2' x 2' cell in a pressure vessel to determine the effect of pressurized operation on cell tolerance. The poisoning effect of hydrogen sulfide was characteristically different from the effects of carbon monoxide, in that it was not manifested by a marginal (e.g., 0 to 50 mV) increase in anode potential but either had no effect or caused catastrophic polarization. Critical levels were derived for hydrogen sulfide as related to cell operating conditions.

  17. H2CO in the Horsehead nebula

    NASA Astrophysics Data System (ADS)

    Guzman, Viviana

    2011-07-01

    Photodissociation region (PDR) models are used to understand the evolution of the far-UV illuminated matter both in our Galaxy and in external galaxies. The spectacular instrumental improvements, which happens in radioastronomy with the advent of Herschel, ALMA and NOEMA, call for matching progresses in PDR modeling. While it is now confirmed that some interstellar species are mostly formed in the gas phase (CO for instance) and others on grains (CH3OH, Garrod et al. 2007), the chemical routes for other species, like H2CO, are still debated because it is likely that solid and gas phase processes are both needed. The availability of well defined observations is essential here to discriminate between chemical assumptions about the important grain surface processes: adsorption, desorption and reactivity. Due to its closeness (~400 pc) and simple geometry, the Horsehead PDR is particularly well suited to investigate the grain surface chemistry. We present observations of 7 transitions of formaldehyde (H2CO) toward two positions: the edge of the nebula exposed to the UV-field (PDR), and a colder region (cold core) shielded from the UV radiation. A non-LTE Montecarlo radiative transfer code is used to determine the H2CO abundance from the observed intensities and line profiles. We find that the H2CO abundance is very similar in the warm PDR and in the cold dense core. The inferred abundances are compared with PDR models, including both gas-phase and grain surface reactions, in order to study the dominant formation routes of H2CO. Pure gas-phase chemistry models fail to reproduce the observed H2CO abundance by a factor ~10 in the PDR, while surface grain chemistry increases the H2CO abundance up to 3 orders of magnitude in the PDR.

  18. Zero liquid carryover whole-body shower vortex liquid/gas separator

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The development and evaluation of a liquid/gas vortex type separator design eliminating liquid and semi-liquid (suds) carryover into air recirculating system were described. Consideration was given to a number of soaps other than the "Miranol JEM" which was the low sudsing soap used in previous test runs of the space shower. Analysis of test parameters and prototype testing resulted in a revised separator configuration and a better understanding of the suds generating mechanism in the wastewater collection system. The final design of the new separator provides for a wider choice of soaps without leading to the problem of "carryover". Furthermore, no changes in separator-to-shower interfaces were required. The new separator was retrofitted on the "space shower" and satisfactorily demonstrated in one-g testing.

  19. The Separation and Identification of Straight Chain Hydrocarbons: An Experiment Using Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Benson, G. A.

    1982-01-01

    An experiment using gas-liquid chromatography is discussed, introducing the student to concept of dead volume and its measurement, idea and use of an internal reference compound, and to linear relationship existing between measurements of a separation on two different stationary phases. (Author/SK)

  20. [Determination of cyclohexanone concentration in the plasma separator by gas chromatography].

    PubMed

    Huang, Min-Ju; Yan, Lin; He, Yan-Ying; Lin, Wei-Cong

    2009-09-01

    This essay is to determine the cyclohexanone concentration of the plasma separator. The compound was introduced into the GC analytical system by the carrier gas. The determination was performed by the measurement of their peak area and by the external standard method.

  1. Chiral porous organic frameworks for asymmetric heterogeneous catalysis and gas chromatographic separation.

    PubMed

    Dong, Jinqiao; Liu, Yan; Cui, Yong

    2014-12-11

    Three chiral robust diene-based porous organic frameworks (POFs) are prepared. POF- is shown to be an efficient heterogeneous catalyst after metallation for asymmetric conjugation addition with up to 93% ee, and it can also function as a new chiral stationary phase for gas chromatographic separation of racemates.

  2. Improved Differential Ion Mobility Separations Using Linked Scans of Carrier Gas Composition and Compensation Field

    NASA Astrophysics Data System (ADS)

    Santiago, Brandon G.; Harris, Rachel A.; Isenberg, Samantha L.; Ridgeway, Mark E.; Pilo, Alice L.; Kaplan, Desmond A.; Glish, Gary L.

    2015-07-01

    Differential ion mobility spectrometry (DIMS) separates ions based on differences in their mobilities in low and high electric fields. When coupled to mass spectrometric analyses, DIMS has the ability to improve signal-to-background by eliminating isobaric and isomeric compounds for analytes in complex mixtures. DIMS separation power, often measured by resolution and peak capacity, can be improved through increasing the fraction of helium in the nitrogen carrier gas. However, because the mobility of ions is higher in helium, a greater number of ions collide with the DIMS electrodes or housing, yielding losses in signal intensity. To take advantage of the benefits of helium addition on DIMS separations and reduce ion losses, linked scans were developed. In a linked scan the helium content of the carrier gas is reduced as the compensation field is increased. Linked scans were compared with conventional compensation field scans with constant helium content for the protein ubiquitin and a tryptic digest of bovine serum albumin (BSA). Linked scans yield better separation of ubiquitin charge states and enhanced peak capacities for the analysis of BSA compared with compensation field scans with constant helium carrier gas percentages. Linked scans also offer improved signal intensity retention in comparison to compensation field scans with constant helium percentages in the carrier gas.

  3. Molecularly Designed Stabilized Asymmetric Hollow Fiber Membranes for Aggressive Natural Gas Separation.

    PubMed

    Liu, Gongping; Li, Nanwen; Miller, Stephen J; Kim, Danny; Yi, Shouliang; Labreche, Ying; Koros, William J

    2016-10-24

    New rigid polyimides with bulky CF3 groups were synthesized and engineered into high-performance hollow fiber membranes. The enhanced rotational barrier provided by properly positioned CF3 side groups prohibited fiber transition layer collapse during cross-linking, thereby greatly improving CO2 /CH4 separation performance compared to conventional materials for aggressive natural gas feeds.

  4. Internally staged permeator prepared from annular hollow fibers for gas separation

    SciTech Connect

    Li, K.; Wang, D.; Li, D.; Teo, W.K.

    1998-04-01

    A polysulfone/polyethersulfone annular hollow-fiber (tube) membrane was prepared using a phase-inversion process, which is useful for further preparation of an internally staged permeator (ISP) for gas separation. This study focused on the techniques of fabricating the polysulfone/polyethersulfone annular-hollow-fiber membranes and its membrane permeators for gas enrichment. Two homogeneous polymer solutions comprising polysulfone/DMAc and polyethersulfone/NMP/water, respectively, were prepared and extruded with a triple-orifice spinneret into an annular-hollow-fiber membrane that possesses two distinct skin layers and is capable of providing two separation stages internally for gas separation. The performance of the ISP fabricated from the prepared annular hollow-fiber membrane was evaluated theoretically and experimentally under co/countercurrent and countercurrent flow patterns for various binary gas mixtures. The mathematical models generally describe satisfactorily the observed experimental results. A parametric study reveals that while, in general, better separation is available at lower values of overall stage cuts, highly purified permeate products could be achieved at higher values of overall stage cuts if the concentration of a permeating component in the feed stock is relatively high.

  5. Ionomers of intrinsic microporosity: in silico development of ionic-functionalized gas-separation membranes.

    PubMed

    Hart, Kyle E; Colina, Coray M

    2014-10-14

    This work presents the predictive molecular simulations of a functionalized polymer of intrinsic microporosity (PIM) with an ionic backbone (carboxylate) and extra-framework counterions (Na(+)) for CO2 gas storage and separation applications. The CO2-philic carboxylate-functionalized polymers are predicted to contain similar degrees of free volume to PIM-1, with Brunauer-Emmett-Teller (BET) surface areas from 510 to 890 m(2)/g, depending on concentration of ionic groups from 100% to 17%. As a result of ionic groups enhancing the CO2 enthalpy of adsorption (to 42-50 kJ/mol), the uptake of the proposed polymers at 293 K exceeded 1.7 mmol/g at 10 kPa and 3.3 mmol/g at 100 kPa for the polymers containing 100% and 50% ionic functional groups, respectively. In addition, CO2/CH4 and CO2/N2 mixed-gas separation performance was evaluated under several industrially relevant conditions, where the IonomIMs are shown to increase both the working capacity and selection performance in certain pressure swing applications (e.g., natural gas separations). These simulations reveal that intrinsically microporous ionomers show great potential as the future of energy-efficient gas-separation polymeric materials.

  6. Ultem®/ZIF-8 mixed matrix membranes for gas separation: Transport and physical properties

    DOE PAGES

    Eiras, Daniel; Labreche, Ying; Pessan, Luiz Antonio

    2016-02-19

    Mixed matrix membranes are promising options for improving gas separation processes. Zeolitic imidazolate frameworks (ZIFs) have a porous structure similar to conventional zeolites, being capable in principle of separating gases based on their differences in kinetic diameter while offering the advantage of having a partial organic character. This partial organic nature improves the compatibility between the sieve and the polymer, and a combination of the mentioned characteristics makes these hybrid materials interesting for the preparation of mixed matrix gas separation membranes. In this context the present work reports the preparation of Ultem®/ZIF-8 mixed matrix membranes and their permeabilities to puremore » CO2, N2 and CH4 gases. A significant increase in permeability with increase in CO2/N2 selectivity was observed for the mixed matrix systems as compared to the properties of the neat Ultem®. Sorption results allowed to speculate that the ZIF-8 framework is not completely stable dimensionally, what influences the separation process by allowing gases with higher kinetic diameter than its nominal aperture to be sorbed and to diffuse through the crystal. Lastly, sorption and diffusion selectivities indicate that the higher separation performance of the mixed matrix membranes is governed by the diffusion process associated with the influence of gas molecule´s geometry.« less

  7. Effect of inlet and outlet flow conditions on natural gas parameters in supersonic separation process.

    PubMed

    Yang, Yan; Wen, Chuang; Wang, Shuli; Feng, Yuqing

    2014-01-01

    A supersonic separator has been introduced to remove water vapour from natural gas. The mechanisms of the upstream and downstream influences are not well understood for various flow conditions from the wellhead and the back pipelines. We used a computational model to investigate the effect of the inlet and outlet flow conditions on the supersonic separation process. We found that the shock wave was sensitive to the inlet or back pressure compared to the inlet temperature. The shock position shifted forward with a higher inlet or back pressure. It indicated that an increasing inlet pressure declined the pressure recovery capacity. Furthermore, the shock wave moved out of the diffuser when the ratio of the back pressure to the inlet one was greater than 0.75, in which the state of the low pressure and temperature was destroyed, resulting in the re-evaporation of the condensed liquids. Natural gas would be the subsonic flows in the whole supersonic separator, if the mass flow rate was less than the design value, and it could not reach the low pressure and temperature for the condensation and separation of the water vapor. These results suggested a guidance mechanism for natural gas supersonic separation in various flow conditions.

  8. Effect of Inlet and Outlet Flow Conditions on Natural Gas Parameters in Supersonic Separation Process

    PubMed Central

    Yang, Yan; Wen, Chuang; Wang, Shuli; Feng, Yuqing

    2014-01-01

    A supersonic separator has been introduced to remove water vapour from natural gas. The mechanisms of the upstream and downstream influences are not well understood for various flow conditions from the wellhead and the back pipelines. We used a computational model to investigate the effect of the inlet and outlet flow conditions on the supersonic separation process. We found that the shock wave was sensitive to the inlet or back pressure compared to the inlet temperature. The shock position shifted forward with a higher inlet or back pressure. It indicated that an increasing inlet pressure declined the pressure recovery capacity. Furthermore, the shock wave moved out of the diffuser when the ratio of the back pressure to the inlet one was greater than 0.75, in which the state of the low pressure and temperature was destroyed, resulting in the re-evaporation of the condensed liquids. Natural gas would be the subsonic flows in the whole supersonic separator, if the mass flow rate was less than the design value, and it could not reach the low pressure and temperature for the condensation and separation of the water vapor. These results suggested a guidance mechanism for natural gas supersonic separation in various flow conditions. PMID:25338207

  9. Performance of a Novel Gas Separation Research Column at Sanford Laboratory

    NASA Astrophysics Data System (ADS)

    Alanson Chiller, Angela; Chiller, Christopher; Mei, Dongming

    2014-03-01

    A world-wide rise in demand for ultrapure materials has necessitated innovation in the production of low impurity and isotopically separated materials that either has not been utilized in these new applications or relies on aging or energy intensive methods. These materials are sought after for large physics investigations, nuclear non-proliferation detection industries, medical imaging and new frontiers in electronic applications. Techniques in separating and purifying nuclear magnetic resonance isotopes of carbon, oxygen, xenon, krypton, and nitrogen are being developed at Sanford Laboratory, Lead, SD. A two-meter laboratory scale selective phase change column designed specifically for real-time sampling of the gas space at specific temperature and pressure is operated at gas/liquid and gas/solid equilibrium temperatures and pressures for selected gases. We report initial results and future applications. Research Funded by SD Governors 2010 Center.

  10. Spontaneous separation of large-spin Fermi gas in the harmonic trap: a density functional study

    PubMed Central

    Sun, Zongli; Gu, Qiang

    2016-01-01

    The component separation of the trapped large-spin Fermi gas is studied within density functional theory. The ground state and ferromagnetic transition in the gas, with and without the spin mixing collision, are calculated. In the absence of spin mixing, two patterns of separation are observed as the interaction between atoms increases, whereas only one of them corresponds to a ferromagnetic transition. The phase diagram suggests that the pattern which the system chooses depends on the interaction strength in the collision channels. With the presence of spin mixing, the distribution of phase region changes because of the interplay between different collision channels. Specifically, the spin exchange benefits the FM transition, while it suppresses the component separation of CS-II pattern. PMID:27549012

  11. Recent progress of chiral stationary phases for separation of enantiomers in gas chromatography.

    PubMed

    Xie, Sheng-Ming; Yuan, Li-Ming

    2017-01-01

    Chromatography techniques based on chiral stationary phases are widely used for the separation of enantiomers. In particular, gas chromatography has developed rapidly in recent years due to its merits such as fast analysis speed, lower consumption of stationary phases and analytes, higher column efficiency, making it a better choice for chiral separation in diverse industries. This article summarizes recent progress of novel chiral stationary phases based on cyclofructan derivatives and chiral porous materials including chiral metal-organic frameworks, chiral porous organic frameworks, chiral inorganic mesoporous materials, and chiral porous organic cages in gas chromatography, covering original research papers published since 2010. The chiral recognition properties and mechanisms of separation toward enantiomers are also introduced.

  12. Porous anionic indium-organic framework with enhanced gas and vapor adsorption and separation ability.

    PubMed

    Huang, Yuanbiao; Lin, Zujin; Fu, Hongru; Wang, Fei; Shen, Min; Wang, Xusheng; Cao, Rong

    2014-09-01

    A three-dimensional microporous anionic metal-organic framework (MOF) (Et4N)3[In3(TATB)4] (FJI-C1, H3TATB=4,4',4''-s-triazine-2,4,6-triyltribenzoic acid) with large unit cell volume has been synthesized. Assisted by the organic cation group Et4N in the pores of the compound, FJI-C1 not only shows high adsorption uptakes of C2 and C3 hydrocarbons, but also exhibits highly selective separation of propane, acetylene, ethane, and ethylene from methane at room temperature. Furthermore, it also exhibits high separation selectivity for propane over C2 hydrocarbons and acetylene can be readily separated from their C2 hydrocarbons mixtures at low pressure due to the high selectivity for C2H2 in comparison to C2H4 and C2H6. In addition, FJI-C1 with hydrophilic internal pores surfaces shows highly efficient adsorption separation of polar molecules from nonpolar molecules. Notably, it exhibits high separation selectivity for benzene over cyclohexane due to the π-π interactions between benzene molecules and s-triazine rings of the porous MOF.

  13. Internal surface modification of zeolite MFI particles and membranes for gas separation

    NASA Astrophysics Data System (ADS)

    Kassaee, Mohamad H.

    Zeolites are a well-known class of crystalline oxide materials with tunable compositions and nanoporous structures, and have been used extensively in catalysis, adsorption, and ion exchange. The zeolite MFI is one of the well-studied zeolites because it has a pore size and structure suitable for separation or chemical conversion of many industrially important molecules. I synthesized MFI membranes with [h0h] out-of-plane orientation on α-alumina supports. The membranes were modified by the same procedures as used for MFI particles and with 1-butanol, 3-amino-1-propanol, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. The existence of functional groups in the pores of the zeolite was confirmed by PA-FTIR measurements. Permeation measurements of H2, N2, CO2, CH 4, and SF6, were performed at room temperature before and after modification. Permeation of n-butane, and i-butane were measured before and after modification with 1-butanol. For all of the studied gases, gas permeances decreased by 1-2 orders of magnitude compared to bare MFI membranes for modified membranes. This is a strong indication that the organic species in the MFI framework are interacting with or blocking the gas molecule transport through the MFI pores. The CO2/CH 4 permeation selectivity was close to the Knudsen selectivity (0.6) for the membranes before modification. CO2/CH4 selectivity increased for MFI/benzenemethanol modified membrane (1.0), whereas it decreased for the MFI/2-[(2-aminoethyl)amino]ethanol modified membrane (0.5). MFI/benzenemethanol crystals were shown to have a highest sorption capacity for CH4, whereas, MFI/2-[(2-aminoethyl)amino]ethanol crystals were shown to have a highest sorption capacity for CO2 over all other studied molecules Higher sorption of CH4 in MFI/benzenemethanol and higher sorption of CO2 in MFI/2-[(2-aminoethyl)amino]ethanol and their strong binding to the modified membrane are likely the reasons for observing higher and lower CO2/CH4 permeation

  14. Decarb/Desal: Separation of Carbon Dioxide from Flue Gas with Simultaneous Fresh Water Production

    SciTech Connect

    Aines, R; Bourcier, W

    2009-10-21

    If fossil fuels continue to be a major part of the world's energy supply, effective means must be developed to deal with the carbon emissions. Geologic sequestration of supercritical CO{sub 2} is expected to play a major role in mitigating this problem. Separating carbon dioxide from other gases is the most costly aspect of schemes for geologic sequestration. That cost is driven by the complexity and energy intensity of current chemical-stripping methods for separating carbon dioxide. Our experience in water treatment technology indicated that an entirely new approach could be developed, taking advantage of water's propensity to separate gases that ionize in water (like CO{sub 2}) from those that do not (like N{sub 2}). Even though water-based systems might not have the extreme selectivity of chemicals like substituted amines used in industrial systems today, they have the potential to tolerate NO{sub x}, SO{sub x}, and particulates while also producing clean drinking water as a valuable byproduct. Lower capital cost, broader range of applicability, environmental friendliness, and revenue from a second product stream give this approach the potential to significantly expand the worldwide application of carbon separation for geologic sequestration. Here we report results for separation of CO{sub 2} from flue gas by two methods that simultaneously separate carbon dioxide and fresh water: ionic pumping of carbonate ions dissolved in water, and thermal distillation. The ion pumping method dramatically increases dissolved carbonate ion in solution and hence the overlying vapor pressure of CO{sub 2} gas, allowing its removal as a pure gas. We have used two common water treatment methods to drive the ion pumping approach, reverse osmosis and electrodialysis to produce pure CO{sub 2}. This novel approach to increasing the concentration of the extracted gas permits new approaches to treating flue gas, because the slightly basic water used as the extraction medium is

  15. Gas-liquid phase separation in oppositely charged colloids: stability and interfacial tension.

    PubMed

    Fortini, Andrea; Hynninen, Antti-Pekka; Dijkstra, Marjolein

    2006-09-07

    We study the phase behavior and the interfacial tension of the screened Coulomb (Yukawa) restricted primitive model (YRPM) of oppositely charged hard spheres with diameter sigma using Monte Carlo simulations. We determine the gas-liquid and gas-solid phase transitions using free energy calculations and grand-canonical Monte Carlo simulations for varying inverse Debye screening length kappa. We find that the gas-liquid phase separation is stable for kappasigmagas-liquid interfacial tension using grand-canonical Monte Carlo simulations. The interfacial tension decreases upon increasing the range of the interaction. In particular, we find that simple scaling can be used to relate the interfacial tension of the YRPM to that of the restricted primitive model, where particles interact with bare Coulomb interactions.

  16. Variable-temperature cryogenic trap for the separation of gas mixtures

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.

    1978-01-01

    The paper describes a continuous variable-temperature U-shaped cold trap which can both purify vacuum-line combustion products for subsequent stable isotopic analysis and isolate the methane and ethane constituents of natural gases. The canister containing the trap is submerged in liquid nitrogen, and, as the gas cools, the gas mixture components condense sequentially according to their relative vapor pressures. After the about 12 min required for the bottom of the trap to reach the liquid-nitrogen temperature, passage of electric current through the resistance wire wrapped around the tubing covering the U-trap permits distillation of successive gas components at optimal temperatures. Data on the separation achieved for two mixtures, the first being typical vacuum-line combustion products of geochemical samples such as rocks and the second being natural gas, are presented, and the thermal behavior and power consumption are reported.

  17. H_2CO in the Horsehead nebula

    NASA Astrophysics Data System (ADS)

    Guzman, V.; Pety, J.; Goicoechea, J. R.; Gerin, M.; Roueff, E.

    2011-05-01

    Photodissociation region (PDR) models are used to understand the evolution of the far-UV illuminated matter both in our Galaxy and in external galaxies. The spectacular instrumental improvements, which happens in radioastronomy with the advent of Herschel, ALMA and NOEMA, call for matching progresses in PDR modeling. While it is now confirmed that some interstellar species are mostly formed in the gas phase (CO for instance) and others on grains (CH_3OH), the chemical routes for other species, like H_2CO, are still debated because it is likely that solid and gas phase processes are both needed. The availability of well defined observations is essential here to discriminate between chemical assumptions about the important grain surface processes: adsorption, desorption and reactivity. Due to its closeness (~400 pc) and simple geometry, the Horsehead PDR is particularly well suited to investigate the grain surface chemistry. We present observations of 7 transitions of formaldehyde (H_2CO) toward two positions: the edge of the nebula exposed to the UV-field (PDR), and a colder region (cold core) shielded from the UV radiation. A non-LTE Montecarlo radiative transfer code is used to determine the H2CO abundance from the observed intensities and line profiles. We find that the H_2CO abundance is very similar in the warm PDR and in the cold dense core. The inferred abundances are compared with PDR models, including both gas-phase and grain surface reactions, in order to study the dominant formation routes of H_2CO. Pure gas-phase chemistry models fail to reproduce the observed H2CO abundance by a factor ~10 in the PDR, while surface grain chemistry successfully reproduces the observed abundance.

  18. High Temperature Polybenzimidazole Hollow Fiber Membranes for Hydrogen Separation and Carbon Dioxide Capture from Synthesis Gas

    DOE PAGES

    Singh, Rajinder P.; Dahe, Ganpat J.; Dudeck, Kevin W.; ...

    2014-12-31

    Sustainable reliance on hydrocarbon feedstocks for energy generation requires CO₂ separation technology development for energy efficient carbon capture from industrial mixed gas streams. High temperature H₂ selective glassy polymer membranes are an attractive option for energy efficient H₂/CO₂ separations in advanced power production schemes with integrated carbon capture. They enable high overall process efficiencies by providing energy efficient CO₂ separations at process relevant operating conditions and correspondingly, minimized parasitic energy losses. Polybenzimidazole (PBI)-based materials have demonstrated commercially attractive H₂/CO₂ separation characteristics and exceptional tolerance to hydrocarbon fuel derived synthesis (syngas) gas operating conditions and chemical environments. To realize a commerciallymore » attractive carbon capture technology based on these PBI materials, development of high performance, robust PBI hollow fiber membranes (HFMs) is required. In this work, we discuss outcomes of our recent efforts to demonstrate and optimize the fabrication and performance of PBI HFMs for use in pre-combustion carbon capture schemes. These efforts have resulted in PBI HFMs with commercially attractive fabrication protocols, defect minimized structures, and commercially attractive permselectivity characteristics at IGCC syngas process relevant conditions. The H₂/CO₂ separation performance of these PBI HFMs presented in this document regarding realistic process conditions is greater than that of any other polymeric system reported to-date.« less

  19. High Temperature Polybenzimidazole Hollow Fiber Membranes for Hydrogen Separation and Carbon Dioxide Capture from Synthesis Gas

    SciTech Connect

    Singh, Rajinder P.; Dahe, Ganpat J.; Dudeck, Kevin W.; Welch, Cynthia F.; Berchtold, Kathryn A.

    2014-12-31

    Sustainable reliance on hydrocarbon feedstocks for energy generation requires CO₂ separation technology development for energy efficient carbon capture from industrial mixed gas streams. High temperature H₂ selective glassy polymer membranes are an attractive option for energy efficient H₂/CO₂ separations in advanced power production schemes with integrated carbon capture. They enable high overall process efficiencies by providing energy efficient CO₂ separations at process relevant operating conditions and correspondingly, minimized parasitic energy losses. Polybenzimidazole (PBI)-based materials have demonstrated commercially attractive H₂/CO₂ separation characteristics and exceptional tolerance to hydrocarbon fuel derived synthesis (syngas) gas operating conditions and chemical environments. To realize a commercially attractive carbon capture technology based on these PBI materials, development of high performance, robust PBI hollow fiber membranes (HFMs) is required. In this work, we discuss outcomes of our recent efforts to demonstrate and optimize the fabrication and performance of PBI HFMs for use in pre-combustion carbon capture schemes. These efforts have resulted in PBI HFMs with commercially attractive fabrication protocols, defect minimized structures, and commercially attractive permselectivity characteristics at IGCC syngas process relevant conditions. The H₂/CO₂ separation performance of these PBI HFMs presented in this document regarding realistic process conditions is greater than that of any other polymeric system reported to-date.

  20. Examination of optimal separator shape of polymer electrolyte fuel cell with numerical analysis including the effect of gas flow through gas diffusion layer

    NASA Astrophysics Data System (ADS)

    Inoue, Gen; Matsukuma, Yosuke; Minemoto, Masaki

    This work concentrates on the effects of channel depth and separator shape on cell output performance, current density distribution and gas flow condition in various conditions with PEFC numerical analysis model including gas flow through GDL. When GDL effective porosity was small, the effect of gas flow through GDL which was changed by channel depth on cell output performance became large. However, current density distribution was ununiform. As GDL permeability became larger, cell output density increased, but current density and gas flow rate distribution were ununiform. From the results of changing the gas flow rate, it was found that the ratio of the minimum gas flow rate to the inlet flow rate depended on channel depth. Furthermore, the optimal separator, which increased output density and made the current density distribution and gas flow rate distribution uniform, was examined. It was also found that cell performance had possible to be developed by improving the turning point of the serpentine separator.

  1. Intensification of heat exchange in a device for gas-dynamic energy separation

    NASA Astrophysics Data System (ADS)

    Leontiev, A. I.; Burtsev, S. A.

    2016-11-01

    The operating efficiency of a gas-dynamic energy-separation device is analyzed, and it is shown that it can be improved if we deposit a regular relief on the wall separating the supersonic and subsonic channels. To decrease the total pressure losses on the side of the supersonic channel, shallow spherical dimples (stampings) are deposited, creating spherical ledges in the subsonic channel because of the small thickness of the wall. The calculation technique is modernized, and modeling is carried out, which shows that by introducing intensified heat exchange, it is possible to improve the efficiency of this device by 1.2-1.4 times in air and in natural gas with a simultaneous decrease in the device size by 20-25%.

  2. Intrinsically microporous polyesters from betulin - toward renewable materials for gas separation made from birch bark.

    PubMed

    Jeromenok, Jekaterina; Böhlmann, Winfried; Antonietti, Markus; Weber, Jens

    2011-11-15

    Betulin, an abundant triterpene, can be extracted from birch bark and can be used as a renewable monomer in the synthesis of microporous polyesters. Cross-linked networks and hyperbranched polymers are accessible by an A(2) + B(3) reaction, with betulin being the A(2) monomer and B(3) being a trifunctional acid chloride. Reaction of betulin with a diacid dichloride results in linear, soluble polyesters. The present communication proves that the polyreaction follows the classic schemes of polycondensation reactions. The resulting polymers are analyzed with regard to their micro-porosity by gas sorption, NMR spectroscopy, and X-ray scattering methods. The polymers feature intrinsic microporosity, having ultrasmall pores, which makes them candidates for gas separation membranes, e.g., for the separation of CO(2) from N(2) .

  3. Synthesis and Characterization of Thiazolium-Based Room Temperature Ionic Liquids for Gas Separations

    SciTech Connect

    Hillesheim, Patrick C; Mahurin, Shannon Mark; Fulvio, Pasquale F; Yeary, Joshua S; Oyola, Yatsandra; Jiang, Deen; Dai, Sheng

    2012-01-01

    A series of novel thiazolium-bis(triflamide) based ionic liquids has been synthesized and characterized. Physicochemical properties of the ionic liquids such as thermal stability, phase transitions, and infrared spectra were analysed and compared to the imidazolium-based congeners. Several unique classes of ancillary substitutions are examined with respect to impacts on overall structure, in addition to their carbon dioxide absorption properties in supported ionic-liquid membranes for gas separation.

  4. Synthesis and Characterization of Thiazolium-Based Room Temperature Ionic Liquids for Gas Separations

    SciTech Connect

    Hillesheim, PC; Mahurin, SM; Fulvio, PF; Yeary, JS; Oyola, Y; Jiang, DE; Dai, S

    2012-09-05

    A series of novel thiazolium-bis(triflamide) based ionic liquids has been synthesized and characterized. Physicochemical properties of the ionic liquids such as thermal stability, phase transitions, and infrared spectra were analyzed and compared to the imidazolium-based congeners. Several unique classes of ancillary substitutions are examined with respect to impacts on overall structure, in addition to their carbon dioxide absorption properties in supported ionic-liquid membranes for gas separation.

  5. Mixed-matrix membranes incorporated with porous shape-persistent organic cages for gas separation.

    PubMed

    Mao, Hongchao; Zhang, Suobo

    2017-03-15

    There has been much recent interest in the use of porous materials derived from self-assembling, shape-persistent organic cages due to their solubility and easy post-synthetic modification. Herein we report the preparation of novel mixed-matrix membranes (MMMs) employing the porous organic cage Noria and its derivatives Noria-Boc and Noria-CO(t)Bu as the fillers, and a fluorine containing polyimide, 6FDA-DAM, as the polymeric matrix. The physical structures and properties of Noria and its derivatives were measured and investigated. Noria with substituents of Boc (cleaved by thermal treatment during the process of membrane fabrication) and CO(t)Bu groups tend to show much better compatibility with polyimide than Noria itself, resulting in homogeneous dispersion of nanoaggregates and fine adhesion between the two phases in the derived Noria/6FDA-DAM and Noria-CO(t)Bu/6FDA-DAM MMMs. Gas permeation tests revealed that Noria and Noria-CO(t)Bu nanoparticles have different effect on gas separation performance of MMMs. The introduction of Noria into 6FDA-DAM tends to enhance CO2/CH4 selectivity and thus improve its gas separation properties, though a decrease in the observed permeability could be observed. In contrast, the introduction of Noria-CO(t)Bu with higher surface area and larger pores tends to increase the free volume and gas permeability of MMMs. These results show that both the morphology and the gas separation properties of MMMs could be tuned by tailoring the structures of porous organic cages.

  6. Macroscopic nanoporous graphene membranes for molecular-sieving-based gas separation

    NASA Astrophysics Data System (ADS)

    Boutilier, Michael; Karnik, Rohit; Hadjiconstantinou, Nicolas

    2016-11-01

    Nanoporous graphene membranes have the potential to exceed permeance and selectivity limits of existing gas separation membranes. This is made possible by the atomic thickness of the material, which can support sub-nanometer pores that enable molecular sieving while presenting low resistance to permeate flow. The feasibility of gas separation by graphene nanopores has been demonstrated experimentally on micron-scale areas of graphene. However, scaling up to macroscopic membrane areas presents significant challenges, including graphene imperfections and control of the selective nanopore size distribution across large areas. Towards this goal, gas permeance experiments are conducted on single and few layer graphene membranes to understand leakage pathways and a model is developed to predict conditions under which molecular sieving can occur in macroscopic membranes. Approaches to seal or mitigate the effects of micron and nanometer scale defects in graphene are investigated and methods of creating a high density of selectively permeable nanopores are explored. Experimental results demonstrating separation ratios exceeding the Knudsen effusion limit, indicating molecular sieving in agreement with the model predictions, are presented and discussed.

  7. Separation and Detection of Toxic Gases with a Silicon Micromachined Gas Chromatography System

    NASA Technical Reports Server (NTRS)

    Kolesar, Edward S.; Reston, Rocky R.

    1995-01-01

    A miniature gas chromatography (GC) system was designed and fabricated using silicon micromachining and integrated circuit (IC) processing techniques. The silicon micromachined gas chromatography system (SMGCS) is composed of a miniature sample injector that incorporates a 10 microliter sample loop; a 0.9 meter long, rectangular shaped (300 micrometer width and 10 micrometer height) capillary column coated with a 0.2 micrometer thick copper phthalocyanine (CuPc) stationary phase; and a dual detector scheme based upon a CuPc-coated chemiresistor and a commercially available 125 micrometer diameter thermal conductivity detector (TCD) bead. Silicon micromachining was employed to fabricate the interface between the sample injector and the GC column, the column itself, and the dual detector cavity. A novel IC thin-film processing technique was developed to sublime the CuPc stationary phase coating on the column walls that were micromachined in the host silicon wafer substrate and Pyrex (r) cover plate, which were then electrostatically bonded together. The SMGCS can separate binary gas mixtures composed of parts-per-million (ppm) concentrations of ammonia (NH3) and nitrogen dioxide (NO2) when isothermally operated (55-80 degrees C). With a helium carrier gas and nitrogen diluent, a 10 microliter sample volume containing ammonia and nitrogen dioxide injected at 40 psi ((2.8 x 10(exp 5)Pa)) can be separated in less than 30 minutes.

  8. Gas Separation Membranes Derived from High-Performance Immiscible Polymer Blends Compatibilized with Small Molecules.

    PubMed

    Panapitiya, Nimanka P; Wijenayake, Sumudu N; Nguyen, Do D; Huang, Yu; Musselman, Inga H; Balkus, Kenneth J; Ferraris, John P

    2015-08-26

    An immiscible polymer blend comprised of high-performance copolyimide 6FDA-DAM:DABA(3:2) (6FDD) and polybenzimidazole (PBI) was compatibilized using 2-methylimidazole (2-MI), a commercially available small molecule. Membranes were fabricated from blends of 6FDD:PBI (50:50) with and without 2-MI for H2/CO2 separations. The membranes demonstrated a matrix-droplet type microstructure as evident with scanning electron microscopy (SEM) imaging where 6FDD is the dispersed phase and PBI is the continuous phase. In addition, membranes with 2-MI demonstrated a uniform microstructure as observed by smaller and more uniformly dispersed 6FDD domains in contrast to 6FDD:PBI (50:50) blend membranes without 2-MI. This compatibilization effect of 2-MI was attributed to interfacial localization of 2-MI that lowers the interfacial energy similar to a surfactant. Upon the incorporation of 2-MI, the H2/CO2 selectivity improved remarkably, compared to the pure blend, and surpassed the Robeson's upper bound. To our knowledge, this is the first report of the use of a small molecule to compatibilize a high-performance immiscible polymer blend. This approach could afford a novel class of membranes in which immiscible polymer blends can be compatibilized in an economical and convenient fashion.

  9. Metal-organic framework nanosheets in polymer composite materials for gas separation

    PubMed Central

    Seoane, Beatriz; Miro, Hozanna; Corma, Avelino; Kapteijn, Freek; Llabrés i Xamena, Francesc X.; Gascon, Jorge

    2014-01-01

    Composites incorporating two-dimensional nanostructures within polymeric matrices hold potential as functional components for several technologies, including gas separation. Prospectively, employing metal-organic-frameworks (MOFs) as versatile nanofillers would notably broaden the scope of functionalities. However, synthesizing MOFs in the form of free standing nanosheets has proven challenging. We present a bottom-up synthesis strategy for dispersible copper 1,4-benzenedicarboxylate MOF lamellae of micrometer lateral dimensions and nanometer thickness. Incorporating MOF nanosheets into polymer matrices endows the resultant composites with outstanding CO2 separation performance from CO2/CH4 gas mixtures, together with an unusual and highly desired increment in the separation selectivity with pressure. As revealed by tomographic focused-ion-beam scanning-electron-microscopy, the unique separation behaviour stems from a superior occupation of the membrane cross-section by the MOF nanosheets as compared to isotropic crystals, which improves the efficiency of molecular discrimination and eliminates unselective permeation pathways. This approach opens the door to ultrathin MOF-polymer composites for various applications. PMID:25362353

  10. Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow

    SciTech Connect

    Mohan, Ram S.; Shoham, Ovadia

    1999-10-28

    The objective of this five-year project (October, 1997--September, 2002) is to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase I (1997--2000) will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000--2002), the developed GLCC separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

  11. Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow

    SciTech Connect

    Mohan, R.S.; Shoham, O.

    2001-01-18

    The objective of this five-year project (October 1997 - September 2002) was to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project was executed in two phases. Phase I (1997 - 2000) focused on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase included the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000 - 2002), the developed GLCC separator will be tested under high pressure and real crude conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

  12. Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow

    SciTech Connect

    Mohan, R.S.; Shoham, O.

    2001-01-10

    The objective of this five-year project (October 1997--September 2002) was to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project was executed in two phases. Phase I (1997--2000) focused on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase included the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000--2002), the developed GLCC separator will be tested under high pressure and real crude conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

  13. Integrated Cryogenic System for CO2 Separation and Lng Production from Landfill Gas

    NASA Astrophysics Data System (ADS)

    Chang, H. M.; Chung, M. J.; Park, S. B.

    2010-04-01

    An integrated cryogenic system to separate carbon dioxide (CO2) and produce LNG from landfill gas is investigated and designed. The main objective of this design is to eliminate the requirement of a standard CO2 removal process in the liquefaction system such distillation or (temperature or pressure) swing adsorption, and to directly separate carbon dioxide as frost at the liquefying channel of methane. Two identical sets of heat exchangers are installed in parallel and switched alternatively with a time period so that one is in separation-liquefaction mode while the other is in CO2 clean-up mode. A thermal regeneration scheme is presented for the purpose of saving energy and avoiding the stoppage of LNG production followed by the flow switching. The switching period is determined from results of a combined heat and mass transfer analysis on the CO2 freeze-out process.

  14. Field Demonstration of a Membrane Process to Separate Nitrogen from Natural Gas

    SciTech Connect

    Kaaeid Lokhandwala

    2007-03-31

    The original proposal described the construction and operation of a 1 MMscfd treatment system to be operated at a Butcher Energy gas field in Ohio. The gas produced at this field contained 17% nitrogen. During pre-commissioning of the project, a series of well tests showed that the amount of gas in the field was significantly smaller than expected and that the nitrogen content of the wells was very high (25 to 30%). After evaluating the revised cost of the project, Butcher Energy decided that the plant would not be economical and withdrew from the project. Since that time, Membrane Technology and Research, Inc. (MTR) has signed a marketing and sales partnership with ABB Lummus Global, a large multinational corporation. MTR is working with the company's Randall Gas Technology group, a supplier of equipment and processing technology to the natural gas industry. Randall's engineering group found a new site for the project at a North Texas Exploration (NTE) gas processing plant, which met with limited success. However, a small test system was installed at a Twin Bottoms Energy well in Kentucky. This unit operated successfully for six months, and demonstrated the technology's reliability on a small scale. MTR then located an alternative test site with much larger gas flow rates and signed a contract with Towne Exploration in the third quarter of 2006, for a demonstration plant in Rio Vista, California, to be run through May 2007. The demonstration for Towne has already resulted in the sale of two commercial skids to the company; both units will be delivered by the end of 2007. Total sales of nitrogen/natural gas membrane separation units from the partnership with ABB are now approaching $4.0 million.

  15. Gas Chromatographic Separation of an Acetylene Vinyl Fluoride-Difluoroethane Mixture on Triethylene Glycol and Silicone Oil,

    DTIC Science & Technology

    The purpose of the research was to study gas-chromatographic separation of impurities of acetylene and difluoroethane in vinyl fluoride obtained by...and difluoroethane . All the components are separated, and the criteria of separation of acetylene-vinyl fluoride and vinyl fluoride- difluoroethane

  16. Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): Degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Garland, R. M.; Pöschl, U.

    2009-12-01

    We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals. The model is based on multiple experimental studies of PAH degradation and on the PRA framework (Pöschl-Rudich-Ammann, 2007) for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude (Kads,O3 ≍ 10-15-10-13 cm3), and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude (kSLR,PAH,O3 ≍ 10-18-10-17 cm2 s-1). The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller (Kads,H2O ≍ 10-18-10-17 cm3). The desorption lifetimes and adsorption enthalpies inferred from the Langmuir adsorption constants suggest chemisorption of NO2 and O3 and physisorption of H2O. Note, however, that the exact reaction mechanisms, rate limiting steps and possible intermediates still remain to be resolved (e.g., surface diffusion and formation of O atoms or O3- ions at the surface). The K2-SURF model enables the calculation of ozone uptake coefficients, γO3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of γO3 on time and gas phase composition, with different characteristics under dilute atmospheric and

  17. Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Garland, R. M.; Pöschl, U.

    2009-09-01

    We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals. The model is based on multiple experimental studies of PAH degradation and on the PRA framework (Pöschl et al., 2007) for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude (Kads,O3≍10-15-10-13 cm3), and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude (kSLR,PAH,O3≍10-18-10-17 cm2 s-1). The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller (Kads,H2O≍10-18-10-17 cm3). The desorption lifetimes and adsorption enthalpies inferred from the Langmuir adsorption constants suggest chemisorption of NO2 and O3 - possibly in the form of O atoms - and physisorption of H2O. The K2-SURF model enables the calculation of ozone uptake coefficients, γO3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of γO3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, γO3 of PAH-coated aerosol particles are expected to be in the range of 10-6-10-5. At ambient temperatures, NO2 alone

  18. Antiproton stopping in H2 and H2O

    NASA Astrophysics Data System (ADS)

    Bailey, J. J.; Kadyrov, A. S.; Abdurakhmanov, I. B.; Fursa, D. V.; Bray, I.

    2015-11-01

    Stopping powers of antiprotons in H2 and H2O targets are calculated using a semiclassical time-dependent convergent close-coupling method. In our approach the H2 target is treated using a two-center molecular multiconfiguration approximation, which fully accounts for the electron-electron correlation. Double-ionization and dissociative ionization channels are taken into account using an independent-event model. The vibrational excitation and nuclear scattering contributions are also included. The H2O target is treated using a neonization method proposed by C. C. Montanari and J. E. Miraglia [J. Phys. B 47, 015201 (2014), 10.1088/0953-4075/47/1/015201], whereby the ten-electron water molecule is described as a dressed Ne-like atom in a pseudospherical potential. Despite being the most comprehensive approach to date, the results obtained for H2 only qualitatively agree with the available experimental measurements.

  19. Electronic states and potential energy surfaces of H2Te, H2Po, and their positive ions

    NASA Astrophysics Data System (ADS)

    Sumathi, K.; Balasubramanian, K.

    1990-06-01

    Geometries, bond energies, ionization potentials, dipole moments, other one-electron properties, and potential energy surfaces of six valence electronic states of H2Te and H2Po species are obtained using the relativistic complete active space multiconfiguration self-consistent field (CASSCF) followed by full second-order configuration interaction (SOCI) and relativistic configuration interaction (RCI) calculations including spin-orbit coupling. In addition, Rydberg states of H2Te and H2Se are studied to interpret the experimental spectra. The potential energy surfaces of two electronic states of H2Te+ and H2Po+ are obtained. The ground states of both H2Te and H2Po are found to be of X 1A1(A1) symmetry with bent (C2v) equilibrium geometries of H2Te:re =1.668 Å, θe=91.2°; and H2Po:re =1.835 Å and θe=90.9°. The ground states of H2Te+ and H2Po+ are X 2B1 with H2Te+:re =1.676 Å, θe=90.7° and H2Po+:re =1.828 Å and θe=88°. The De (HTe-H) and De (HPo-H) including spin-orbit effects are calculated as 63.2 and 39.4 kcal/mol, respectively. The X 2B1(E)-A 2A1(E) energy separations of H2Te+ and H2Po+ ions are calculated as 66.6 and 76 kcal/mol, respectively. The adiabatic IPs of H2Te and H2Po are calculated as 8.47 and 7.79 eV, respectively. In addition CASSCF/SOCI/RCI calculations are also carried out on the X 2Π3/2 and 2Π1/2 states of TeH and PoH diatomics. The X 2Π3/2-2Π1/2 energy separations of TeH and PoH are computed as 3710 and 9920 cm-1, respectively. Spin-orbit effects are thus found to be very significant for PoH and H2Po. All excited states of H2Te and H2Po are above 3.7 and 3.1 eV, respectively. Properties and energy separations of H2Te and H2Po are compared with the lighter group (VI) H2Ch species.

  20. Compound Natural Gas Hydrate: A Natural System for Separation of Hydrate-Forming Gases

    NASA Astrophysics Data System (ADS)

    Max, M. D.; Osegovic, J. P.

    2007-12-01

    Natural processes that separate materials from a mixture may exert a major influence on the development of the atmospheres and surfaces of planets, moons, and other planetary bodies. Natural distillation and gravity separation, amongst others, are well known means of differentiating materials through liquid-gas partitioning. One of the least known attributes of clathrate (gas) hydrates is their potential effect on the evolution of planetary system oceans and atmospheres. Gas hydrates separate gases from mixtures of gases by concentrating preferred hydrate-forming materials (HFM) guests within the water-molecule cage structure of crystalline hydrate. Different HFMs have very different fields of stability. When multiple hydrate formers are present, a preference series based on their selective uptake exists. Compound hydrate, which is formed from two or more species of HFM, extract preferred HFM from a mixture in very different proportions to their relative percentages of the original mixture. These compound hydrates can have different formation and dissociation conditions depending on the evolution of the environment. That is, the phase boundary of the compound hydrate that is required for dissociation lies along a lower pressure - higher temperature course. Compound hydrates respond to variations in temperature, pressure, and HFM composition. On Earth, the primary naturally occurring hydrate of interest to global climate modeling is methane hydrate. Oceanic hydrate on Earth is the largest store of carbon in the biosphere that is immediately reactive to environmental change, and is capable of releasing large amounts of methane into the atmosphere over a short geological time span. Hydrate formation is essentially metastable and is very sensitive to environmental change and to gas flux. Where natural variations in temperature and pressure varies so that hydrate will form and dissociate in some cyclical manner, such as in oceans where sea level is capable of rising and

  1. The tropospheric gas composition of Jupiter's north equatorial belt (NH3, PH3, CH3D, GeH4, H2O) and the Jovian D/H isotropic ratio

    NASA Technical Reports Server (NTRS)

    Kunde, V.; Hanel, R.; Maguire, W.; Gautier, D.; Baluteau, J. P.; Marten, A.; Chedin, A.; Husson, N.; Scott, N.

    1982-01-01

    The gas composition of the troposphere of Jupiter in the clearest regions of the North Equatorial Belt (NEB) was derived from the Voyager 1 IRIS data. The infrared spectrum for this homogeneous cloud free region was modeled to infer altitude profiles for NH3, PH3, GeH4 and H2O. The Profiles for NH3 and PH3 were found to be depleted in the upper troposphere but otherwise in agreement with their solar values at the 1 bar level. The mole fraction for CH3D was determined to be 3.5(+1.0 or -1.3) x 10 to the minus 7th power. The GeH4 mole fraction of 7+ or -2 x 10 to the minus 10th power at the 2 to 3 bar level is a factor of 10 lower than the solar value. The H2O mole fraction is approximately 1 x 0.00001 at the 2.5 bar level and is increasing to approximately 3 x 0.00001 at 4 bars where it is a factor of 30 lower than solar. Using IRIS infrared values for the mole fractions of CH3D and CH4 a value of D/H = 3.6(+1.0 or -1.4)x 0.00001 is derived. Assuming this Jovian D/H ratio is representative of the protosolar nebula, and correcting for chemical galactic evolution, yields a value of 5.5 - 9.0 x 0.00001 for the primordial D/H ratio and an upper limit of 1.8 to 2.4 x 10 to the minus 31st power cu cm for the present day baryon density.

  2. Gas Barrier and Separation Behavior of Graphene Oxide Nanobrick Wall Thin Films

    NASA Astrophysics Data System (ADS)

    Grunlan, Jaime

    2015-03-01

    In many cases, electronics packaging requires electrical conductivity and barrier to oxygen, even under humid conditions. These two properties have simultaneously been realized through the use of surfactant-free aqueous layer-by-layer (LbL) processing, in the form of a polymer composite nanocoating. By layering graphene oxide (GO) with polyethyleneimine (PEI), a ``nano brick wall'' structure has been created, imparting gas barrier properties to the film. Reducing the graphene oxide with a thermal treatment further produces high oxygen barrier in humid conditions and imparts high electrical conductivity (σ ~ 1750 S/m). These thin films (<400 nm) are flexible relative traditional conductive thin films (e.g. ITO), and processing occurs under ambient conditions with water as the only solvent. Additionally, these PEI/GO thin films exhibit H2/CO2 selectivity (>300), making them interesting for gas purification membranes. The flexible nature of the aforementioned thin films, along with their excellent combination of transport properties, make them ideal candidates for use in a broad range of electronics and other packaging applications.

  3. Development of Brazing Technology for Use in High Temperature Gas Separation Equipment

    SciTech Connect

    Weil, K. Scott; Hardy, John S.; Kim, Jin Yong Y.

    2003-04-07

    The development of high-temperature electrochemical devices such as oxygen and hydrogen separators, fuel gas reformers, solid oxide fuel cells, and chemical sensors is part of a rapidly expanding segment of the solid state technology market. These devices employ an ionic conducting ceramic as the active membrane that establishes the electrochemical potential of the device, either under voltage (i.e. to carry out gas separation) or under chemical gradient (to develop an electrical potential and thereby generate electrical power). Because the device operates under an ionic gradient that develops across the electrolyte, hermiticity across this layer is paramount. That is, not only must this thin ceramic membrane be dense with no interconnected porosity, but it must be connected to the rest of the device, typically constructed from a heat resistant alloy, with a high-temperature, gas-tight seal. A significant engineering challenge in fabricating these devices is how to effectively join the thin electrochemically active membrane to the metallic body of the device such that the resulting seal is hermetic, rugged, and stable during continuous high temperature operation.

  4. Rapid separation of beryllium and lanthanide derivatives by capillary gas chromatography

    SciTech Connect

    Harvey, Scott D.; Lucke, Richard B.; Douglas, Matt

    2012-09-04

    Previous studies describe derivatization of metal ions followed by analysis using gas chromatography, usually on packed columns. In many of these studies, stable and volatile derivatives were formed using fluorinated β-diketonate reagents. This paper extends previous work by investigating separations of the derivatives on small-diameter capillary gas chromatography columns and exploring on-fiber, solid-phase microextraction derivatization techniques for beryllium. The β-diketonate used for these studies was 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione. Derivatization of lanthanides also required addition of a neutral donor, dibutyl sulfoxide, in addition to 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione. Unoptimized separations on a 100-μm i.d. capillary column proved capable of rapid separations (within 15 min) of lanthanide derivatives that are adjacent to one another in the periodic table. Full-scan mass spectra were obtained from derivatives containing 5 ng of each lanthanide. Studies also developed a simple on-fiber solid-phase microextraction derivatization of beryllium. Beryllium could be analyzed in the presence of other alkali earth elements (Ba(II) and Sr(II)) without interference. Finally, extension of the general approach was demonstrated for several additional elements (i.e. Cu(II), Cr(III), and Ga(III)).

  5. Mass spectrometric approach for characterizing the disordered tail regions of the histone H2A/H2B dimer.

    PubMed

    Saikusa, Kazumi; Nagadoi, Aritaka; Hara, Kana; Fuchigami, Sotaro; Kurumizaka, Hitoshi; Nishimura, Yoshifumi; Akashi, Satoko

    2015-02-17

    The histone H2A/H2B dimer is a component of nucleosome core particles (NCPs). The structure of the dimer at the atomic level has not yet been revealed. A possible reason for this is that the dimer has three intrinsically disordered tail regions: the N- and C-termini of H2A and the N-terminus of H2B. To investigate the role of the tail regions of the H2A/H2B dimer structure, we characterized behaviors of the H2A/H2B mutant dimers, in which these functionally important disordered regions were depleted, using mass spectrometry (MS). After verifying that the acetylation of Lys residues in the tail regions had little effect on the gas-phase conformations of the wild-type dimer, we prepared two histone H2A/H2B dimer mutants: an H2A/H2B dimer depleted of both N-termini (dN-H2A/dN-H2B) and a dimer with the N- and C-termini of H2A and the N-terminus of H2B depleted (dNC-H2A/dN-H2B). We analyzed these mutants using ion mobility-mass spectrometry (IM-MS) and hydrogen/deuterium exchange mass spectrometry (HDX-MS). With IM-MS, reduced structural diversity was observed for each of the tail-truncated H2A/H2B mutants. In addition, global HDX-MS proved that the dimer mutant dNC-H2A/dN-H2B was susceptible to deuteration, suggesting that its structure in solution was somewhat loosened. A partial relaxation of the mutant's structure was demonstrated also by IM-MS. In this study, we characterized the relationship between the tail lengths and the conformations of the H2A/H2B dimer in solution and gas phases, and demonstrated, using mass spectrometry, that disordered tail regions play an important role in stabilizing the conformation of the core region of the dimer in both phases.

  6. A Mechanistic Study of Chemically Modified Inorganic Membranes for Gas and Liquid Separations

    SciTech Connect

    Way, J Douglas

    2011-01-21

    This final report will summarize the progress made during the period August 1, 1993 - October 31, 2010 with support from DOE grant number DE-FG03-93ER14363. The objectives of the research have been to investigate the transport mechanisms in micro- and mesoporous, metal oxide membranes and to examine the relationship between the microstructure of the membrane, the membrane surface chemistry, and the separation performance of the membrane. Examples of the membrane materials under investigation are the microporous silica hollow fiber membrane manufactured by PPG Industries, chemically modified mesoporous oxide membranes, and polymer membranes containing microporous oxides (mixed matrix membranes). Analytical techniques such as NMR, FTIR and Raman spectroscopy, thermal analysis, and gas adsorption were used to investigate membrane microstructure and to probe the chemical interactions occurring at the gas-membrane interface.

  7. Porous Polymer Networks: Synthesis, Porosity, and Applications in Gas Storage/Separation

    SciTech Connect

    Lu, Weigang; Yuan, Daqiang; Zhao, Dan; Schilling, Christine Inge; Plietzsch, Oliver; Muller, Thierry; Braese, Stefano; Guenther, Johannes; Blumel, Janet; Krishna, Rajamani; Li, Zhen; Zhou, Hong-Cai

    2010-11-09

    Three porous polymer networks (PPNs) have been synthesized by the homocoupling of tetrahedral monomers. Like other hyper-cross-linked polymer networks, these materials are insoluble in conventional solvents and exhibit high thermal and chemical stability. Their porosity was confirmed by N₂ sorption isotherms at 77 K. One of these materials, PPN-3, has a Langmuir surface area of 5323 m² g-1. Their clean energy applications, especially in H₂, CH₄, and CO₂ storage, as well as CO₂/CH₄ separation, have been carefully investigated. Although PPN-1 has the highest gas affinity because of its smaller pore size, the maximal gas uptake capacity is directly proportional to their surface area. PPN-3 has the highest H₂ uptake capacity among these three (4.28 wt %, 77 K). Although possessing the lowest surface area, PPN-1 shows the best CO₂/CH₄ selectivity among them.

  8. Synthesis and Transport Properties of Novel MOF/PIM-1/MOF Sandwich Membranes for Gas Separation.

    PubMed

    Fuoco, Alessio; Khdhayyer, Muhanned R; Attfield, Martin P; Esposito, Elisa; Jansen, Johannes C; Budd, Peter M

    2017-02-11

    Metal-organic frameworks (MOFs) were supported on polymer membrane substrates for the fabrication of composite polymer membranes based on unmodified and modified polymer of intrinsic microporosity (PIM-1). Layers of two different MOFs, zeolitic imidazolate framework-8 (ZIF-8) and Copper benzene tricarboxylate ((HKUST-1), were grown onto neat PIM-1, amide surface-modified PIM-1 and hexamethylenediamine (HMDA) -modified PIM-1. The surface-grown crystalline MOFs were characterized by a combination of several techniques, including powder X-ray diffraction, infrared spectroscopy and scanning electron microscopy to investigate the film morphology on the neat and modified PIM-1 membranes. The pure gas permeabilities of He, H₂, O₂, N₂, CH₄, CO₂ were studied to understand the effect of the surface modification on the basic transport properties and evaluate the potential use of these membranes for industrially relevant gas separations. The pure gas transport was discussed in terms of permeability and selectivity, highlighting the effect of the MOF growth on the diffusion coefficients of the gas in the new composite polymer membranes. The results confirm that the growth of MOFs on polymer membranes can enhance the selectivity of the appropriately functionalized PIM-1, without a dramatic decrease of the permeability.

  9. Separation of particulate from flue gas of fossil fuel combustion and gasification

    DOEpatents

    Yang, Wen-Ching; Newby, Richard A.; Lippert, Thomas E.

    1997-01-01

    The gas from combustion or gasification of fossil fuel contains flyash and other particulate. The flyash is separated from the gas in a plurality of standleg moving granular-bed filter modules. Each module includes a dipleg through which the bed media flows into the standleg. The bed media forms a first filter bed having an upper mass having a first frusto-conical surface in a frusto-conical member at the entrance to the standleg and a lower mass having a second frusto-conical surface of substantially greater area than the first surface after it passes through the standleg. A second filter media bed may be formed above the first filter media bed. The gas is fed tangentially into the module above the first surface. The flyash is captured on the first frusto-conical surface and within the bed mass. The processed gas flows out through the second frusto-conical surface and then through the second filter bed, if present. The bed media is cleaned of the captured flyash and recirculated to the moving granular bed filter. Alternatively, the bed media may be composed of the ash from the combustion which is pelletized to form agglomerates. The ash flows through the bed only once; it is not recycled.

  10. Separation of particulate from flue gas of fossil fuel combustion and gasification

    DOEpatents

    Yang, W.C.; Newby, R.A.; Lippert, T.E.

    1997-08-05

    The gas from combustion or gasification of fossil fuel contains fly ash and other particulates. The fly ash is separated from the gas in a plurality of standleg moving granular-bed filter modules. Each module includes a dipleg through which the bed media flows into the standleg. The bed media forms a first filter bed having an upper mass having a first frusto-conical surface in a frusto-conical member at the entrance to the standleg and a lower mass having a second frusto-conical surface of substantially greater area than the first surface after it passes through the standleg. A second filter media bed may be formed above the first filter media bed. The gas is fed tangentially into the module above the first surface. The fly ash is captured on the first frusto-conical surface and within the bed mass. The processed gas flows out through the second frusto-conical surface and then through the second filter bed, if present. The bed media is cleaned of the captured fly ash and recirculated to the moving granular bed filter. Alternatively, the bed media may be composed of the ash from the combustion which is pelletized to form agglomerates. The ash flows through the bed only once; it is not recycled. 11 figs.

  11. Development of silver impregnated alumina for iodine separation from off-gas streams

    SciTech Connect

    Funabashi, Kiyomi; Fukasawa, Tetsuo; Kikuchi, Makoto

    1995-02-01

    An inorganic iodine adsorbent, silver impregnated alumina (AgA), has been developed to separate iodine effectively from off-gas streams of nuclear facilities and to decrease the volume of waste (spent adsorbent). Iodine removal efficiency was improved at relatively high humidity by using alumina carrier with two different pore diameters. Waste volume reduction was achieved by impregnating relatively large amounts of silver into the alumina pores. The developed adsorbent was tested first with simulated off-gas streams under various experimental conditions and finally with actual off-gas streams of the Karlsruhe reprocessing plant. The decontamination factor (DF) was about 100 with the AgA bed depth of 2cm at 70% relative humidity, which was a DF one order higher than that when AgA with one pore size was used. Iodine adsorption capacity was checked by passing excess iodine into the AgA bed. Values were about 0.12 and 0.35 g-I/cm`-AgA bed for 10 and 24wt% silver impregnated AgA, respectively. The results obtained in this study demonstrated the applicability of the developed AgA to the off-gas treatment system of nuclear facilities.

  12. Finite Element Modeling of Adsorption Processes for Gas Separation and Purification

    SciTech Connect

    Humble, Paul H.; Williams, Richard M.; Hayes, James C.

    2009-09-22

    Pacific Northwest National Laboratory (PNNL) has expertise in the design and fabrication of automated radioxenon collection systems for nuclear explosion monitoring. In developing new systems there is an ever present need to reduce size, power consumption and complexity. Most of these systems have used adsorption based techniques for gas collection and/or concentration and purification. These processes include pressure swing adsorption, vacuum swing adsorption, temperature swing adsorption, gas chromatography and hybrid processes that combine elements of these techniques. To better understand these processes, and help with the development of improved hardware, a finite element software package (COMSOL Multiphysics) has been used to develop complex models of these adsorption based operations. The partial differential equations used include a mass balance for each gas species and adsorbed species along with a convection conduction energy balance equation. These equations in conjunction with multicomponent temperature dependent isotherm models are capable of simulating separation processes ranging from complex multibed PSA processes, and multicomponent temperature programmed gas chromatography, to simple two component temperature swing adsorption. These numerical simulations have been a valuable tool for assessing the capability of proposed processes and optimizing hardware and process parameters.

  13. Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): Degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3

    NASA Astrophysics Data System (ADS)

    Shiraiwa, Manabu; Garland, Rebecca M.; Pöschl, Ulrich

    2010-05-01

    We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals [1]. The model is based on multiple experimental studies of PAH degradation and on the Pöschl-Rudich-Ammann (PRA) framework [2] for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude, and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude. The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller. The desorption lifetimes and adsorption enthalpies suggest chemisorption of NO2 and O3 and physisorption of H2O. Note, however, that the exact reaction mechanisms, rate limiting steps and possible intermediates still remain to be resolved (e.g., surface diffusion and formation of O atoms or O3- ions at the surface). The K2-SURF model enables the calculation of ozone uptake coefficients, γO3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of γO3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, γO3 of PAH-coated aerosol particles are expected to be in the range of 10-6 - 10

  14. Detection of absorption by H2 in molecular clouds: A direct measurement of the H2:CO ratio

    NASA Technical Reports Server (NTRS)

    Lacy, J. H.; Knacke, R.; Geballe, T. R.; Tokunaga, A. T.

    1994-01-01

    Vibrational absorption by H2 and CO has been searched for toward infrared sources embedded in molecular clouds. H2 was detected toward NGC 2024 IRS 2 and possibly toward NGC 2264 (GL 989). CO was detected toward both sources. The results are consistent with the H2 ortho:para ratio being equilibrated at the cloud temperature. Toward NGC 2024, H2:CO = (3700(sub -2600)(sup +3100)) (2 sigma limits), and toward NGC 2264, H2:CO less than 6000. Approximately one-third of all carbon is in gas-phase CO.

  15. High-temperature separation with polymer-coated fiber in packed capillary gas chromatography.

    PubMed

    Saito, Yoshihiro; Ogawa, Mitsuhiro; Imaizumi, Motohiro; Ban, Kazuhiro; Abe, Akira; Takeichi, Tsutomu; Wada, Hiroo; Jinno, Kiyokatsu

    2005-06-01

    High-temperature gas chromatographic separation of several synthetic polymer mixtures with Dexsil-coated fiber-packed columns was studied. A bundle of heat-resistant filaments, Zylon, was longitudinally packed into a short metal capillary, followed by the conventional coating process with Dexsil 300 material. Prior to the packing process the metal capillary was deactivated by the formation of a silica layer. The typical size of the resulting column was 0.3-mm i.d., 0.5-mm o.d., 1-m length, and packed with about 170 filaments of the Dexsil-coated Zylon. The column temperature could be elevated up to 450 degrees C owing to the good thermal stability of the fiber, Dexsil coating, and metal capillary; furthermore, this allowed the separation of low-volatile compounds to be studied.

  16. Chemically Stable Covalent Organic Framework (COF)-Polybenzimidazole Hybrid Membranes: Enhanced Gas Separation through Pore Modulation.

    PubMed

    Biswal, Bishnu P; Chaudhari, Harshal D; Banerjee, Rahul; Kharul, Ulhas K

    2016-03-24

    Highly flexible, TpPa-1@PBI-BuI and TpBD@PBI-BuI hybrid membranes based on chemically stable covalent organic frameworks (COFs) could be obtained with the polymer. The loading obtained was substantially higher (50 %) than generally observed with MOFs. These hybrid membranes show an exciting enhancement in permeability (about sevenfold) with appreciable separation factors for CO2/N2 and CO2/CH4. Further, we found that with COF pore modulation, the gas permeability can be systematically enhanced.

  17. Automation of experiments at the Dubna gas-filled separator of recoil nuclei: Part II

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yu. S.

    2015-03-01

    An application developed in Builder C++ (Windows) for the offline analysis of experimental data from the spectrometer of the gas-filled separator of recoil nuclei (Flerov Laboratory of Nuclear Reactions) based on the double-sided silicon strip detector is discussed. The automatic express method developed for calibrating 48 strips of the silicon position-sensitive detector based on the three most energetic spectral lines from the natYb + 48Ca▭*Th reaction is compared to the results produced by more rigorous calibration methods. The examples of spectra for this reaction and the results of filtering for the proposed calibration algorithm are given.

  18. Membrane process for separating H{sub 2}S from natural gas

    SciTech Connect

    Baker, R.W.

    1995-07-01

    Objective was to develop a membrane process for separating hydrogen sulfide and other impurities (CO{sub 2}, water vapor) from low-quality natural gas. A membrane material was identified with very high H{sub 2}/CH{sub 4} selectivity in the range of 40--60; membrane production was scaled up to commercial size rolls; high-pressure membrane and module development and optimization were completed; and a membrane permeation flux of 4{times}10{sub {minus}6} cm{sup 3}/s{center_dot}cm{sup 2}cmHg, twice as high state-of-the-art cellulose acetate membranes, was achieved.

  19. Diffusible gas transmitter signaling in the copepod crustacean Calanus finmarchicus: identification of the biosynthetic enzymes of nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) using a de novo assembled transcriptome.

    PubMed

    Christie, Andrew E; Fontanilla, Tiana M; Roncalli, Vittoria; Cieslak, Matthew C; Lenz, Petra H

    2014-06-01

    Neurochemical signaling is a major component of physiological/behavioral control throughout the animal kingdom. Gas transmitters are perhaps the most ancient class of molecules used by nervous systems for chemical communication. Three gases are generally recognized as being produced by neurons: nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S). As part of an ongoing effort to identify and characterize the neurochemical signaling systems of the copepod Calanus finmarchicus, the biomass dominant zooplankton in much of the North Atlantic Ocean, we have mined a de novo assembled transcriptome for sequences encoding the neuronal biosynthetic enzymes of these gases, i.e. nitric oxide synthase (NOS), heme oxygenase (HO) and cystathionine β-synthase (CBS), respectively. Using Drosophila proteins as queries, two NOS-, one HO-, and one CBS-encoding transcripts were identified. Reverse BLAST and structural analyses of the deduced proteins suggest that each is a true member of its respective enzyme family. RNA-Seq data collected from embryos, early nauplii, late nauplii, early copepodites, late copepodites and adults revealed the expression of each transcript to be stage specific: one NOS restricted primarily to the embryo and the other was absent in the embryo but expressed in all other stages, no CBS expression in the embryo, but present in all other stages, and HO expressed across all developmental stages. Given the importance of gas transmitters in the regulatory control of a number of physiological processes, these data open opportunities for investigating the roles these proteins play under different life-stage and environmental conditions in this ecologically important species.

  20. Graphitic carbon nitride as high-resolution stationary phase for gas chromatographic separations.

    PubMed

    Zheng, Yunzhong; Qi, Meiling; Fu, Ruonong

    2016-07-08

    This work presents the first example of utilization of graphitic carbon nitride (g-C3N4) as stationary phase for capillary gas chromatographic (GC) separations. The statically coated g-C3N4 column showed the column efficiencies of 3760 plates/m and weak polarity. Its resolving capability and retention behaviours were investigated by using the Grob test mixture, and mixtures of diverse types of analytes, and structural and positional isomers. The results showed superior separation performance of the g-C3N4 stationary phase for some critical analytes and preferential retention for aromatic analytes. Specifically, it exhibited high-resolution capability for aromatic and aliphatic isomers such as methylnaphthalenes and dimethylnaphthalenes, phenanthrene and anthracene and alkane isomers. In addition, g-C3N4 column showed excellent thermal stability up to 280°C and good repeatability with relative standard deviation (RSD) values less than 0.09% for intra-day, below 0.23% for inter-day and in the range of 1.9-8.4% for between-column, respectively. The advantageous separation performance shows the potential of g-C3N4 and related materials as stationary phase in GC and other separation technologies.

  1. Separation of astaxanthin from cells of Phaffia rhodozyma using colloidal gas aphrons in a flotation column.

    PubMed

    Dermiki, Maria; Bourquin, Anne Lise; Jauregi, Paula

    2010-01-01

    The aim of this study is to investigate the separation of astaxanthin from the cells of Phaffia rhodozyma using colloidal gas aphrons (CGA), which are surfactant stabilized microbubbles, in a flotation column. It was reported in previous studies that optimum recoveries are achieved at conditions that favor electrostatic interactions. Therefore, in this study, CGA generated from the cationic surfactant hexadecyl trimethyl ammonium bromide (CTAB) were applied to suspensions of cells pretreated with NaOH. The different operation modes (batch or continuous) and the effect of volumetric ratio of CGA to feed, initial concentration of feed, operating height, and flow rate of CGA on the separation of astaxanthin were investigated. The volumetric ratio was found to have a significant effect on the separation of astaxanthin for both batch and continuous experiments. Additionally, the effect of homogenization of the cells on the purity of the recovered fractions was investigated, showing that the homogenization resulted in increased purity. Moreover, different concentrations of surfactant were used for the generation of CGA for the recovery of astaxanthin on batch mode; it was found that recoveries up to 98% could be achieved using CGA generated from a CTAB solution 0.8 mM, which is below the CTAB critical micellar concentration (CMC). These results offer important information for the scale-up of the separation of astaxanthin from the cells of P. rhodozyma using CGA.

  2. Experimental Research on Gas-Solid Flow in a Square Cyclone Separator with Double Inlets

    NASA Astrophysics Data System (ADS)

    Xiong, B.; Lu, X. F.; Amano, R. S.; Shu, C.

    A square cyclone separator with double inlets was developed for a new type Circulating Fluidized Bed (CFB) boiler arrangement scheme including two furnaces. Experiments on the performance and gas-solid flow recorded by a high-speed photography have been conducted in a cold test rig with a separator cross section 400mm×400mm. Experimental results indicated that with the inlet velocity of 22.4m/s and the inlet solids concentration of 4.9g/m3, the cut size is 15 μm, the critical size is 75μm, and the pressure drop coefficient is 1.7. The performance is also affected by the inlet velocity and solids concentration. The trajectory of particles shows that the particles swirl in the region near the wall and are easily separated. Especially, the instantaneous separation occurred at the corner is very significant for the improvement of the collection efficiency with the high inlet solids concentration for CFB boiler.

  3. DESIGN AND DEVELOPMENT OF GAS-LIQUID CYLINDRICAL CYCLONE COMPACT SEPARATORS FOR THREE-PHASE FLOW

    SciTech Connect

    Dr. Ram S. Mohan; Dr. Ovadia Shoham

    2003-06-25

    The U.S. Department of Energy (DOE) has awarded a five-year (1997-2002) grant (Mohan and Shoham, DE-FG26-97BC15024, 1997) to The University of Tulsa, to develop compact multiphase separation components for 3-phase flow. The research activities of this project have been conducted through cost sharing by the member companies of the Tulsa University Separation Technology Projects (TUSTP) research consortium and the Oklahoma Center for the Advancement of Science and Technology (OCAST). As part of this project, several individual compact separation components have been developed for onshore and offshore applications. These include gas-liquid cylindrical cyclones (GLCC{copyright}), liquid-liquid cylindrical cyclones (LLCC{copyright}), and the gas-liquid-liquid cylindrical cyclones (GLLCC{copyright}). A detailed study has also been completed for the liquid-liquid hydrocyclones (LLHC). Appropriate control strategies have been developed for proper operation of the GLCC{copyright} and LLCC{copyright}. Testing of GLCC{copyright} at high pressure and real crude conditions for field applications is also completed. Limited studies have been conducted on flow conditioning devices to be used upstream of the compact separators for performance improvement. This report presents a brief overview of the activities and tasks accomplished during the 5-year project period, October 1, 1997-March 31, 2003 (including the no-cost extended period of 6 months). An executive summary is presented initially followed by the tasks of the 5-year budget periods. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with some discussions. The findings of this investigation are summarized in the ''Conclusions'' section, followed by relevant references. The publications resulting from this study in the form of MS Theses, Ph.D. Dissertation, Journal Papers and

  4. DESIGN AND DEVELOPMENT OF GAS-LIQUID CYLINDRICAL CYCLONE COMPACT SEPARATORS FOR THREE-PHASE FLOW

    SciTech Connect

    Dr. Ram S. Mohan; Dr. Ovadia Shoham

    2000-04-28

    The objective of this five-year project (October, 1997-September, 2002) is to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase I (1997-2000) will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC{copyright}) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC{copyright}. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000-2002), the developed GLCC{copyright} separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC{copyright} design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP. This report presents a brief overview of the activities and tasks accomplished during the first half year (October 1, 1999-March 31, 2000) of the budget period (October 1, 1999-September 30, 2000). The total tasks of the budget period are given initially, followed by the technical and scientific results achieved till date. The report concludes with a detailed description of the plans for the conduct of the project for the second half year (April 1, 2000-September 30, 2000) of the current budget period.

  5. High performance liquid chromatographic separations of gas oil samples and their hydrotreated products using commercial normal phases.

    PubMed

    Oro, Nicole E; Lucy, Charles A

    2011-10-28

    Three commercially available high performance liquid chromatography columns are used in normal phase or quasi-normal phase mode for the separation of gas oil samples. The columns are tested with 20 analytical standards to determine their suitability for separations of petroleum samples and their ability to separate the nitrogen group-types (pyrrole and pyridine) found in petroleum. The columns studied are polymeric hypercrosslinked polystyrene (HGN), a biphenyl phase, and a Chromegabond "DNAP" column from ES Industries. The HGN column separates gas oils based on both ring structure and heteroatom, while the biphenyl phase has low retention of most compounds studied in quasi-normal phase mode. The "DNAP" column is selective for nitrogen-containing compounds, separating them from PAHs as well as oxygen and sulphur compounds. Retention data of standards on all three columns is shown, along with chromatograms of gas oil samples on the HGN and "DNAP" columns.

  6. Reversed thermo-switchable molecular sieving membranes composed of two-dimensional metal-organic nanosheets for gas separation

    NASA Astrophysics Data System (ADS)

    Wang, Xuerui; Chi, Chenglong; Zhang, Kang; Qian, Yuhong; Gupta, Krishna M.; Kang, Zixi; Jiang, Jianwen; Zhao, Dan

    2017-02-01

    It is highly desirable to reduce the membrane thickness in order to maximize the throughput and break the trade-off limitation for membrane-based gas separation. Two-dimensional membranes composed of atomic-thick graphene or graphene oxide nanosheets have gas transport pathways that are at least three orders of magnitude higher than the membrane thickness, leading to reduced gas permeation flux and impaired separation throughput. Here we present nm-thick molecular sieving membranes composed of porous two-dimensional metal-organic nanosheets. These membranes possess pore openings parallel to gas concentration gradient allowing high gas permeation flux and high selectivity, which are proven by both experiment and molecular dynamics simulation. Furthermore, the gas transport pathways of these membranes exhibit a reversed thermo-switchable feature, which is attributed to the molecular flexibility of the building metal-organic nanosheets.

  7. Reversed thermo-switchable molecular sieving membranes composed of two-dimensional metal-organic nanosheets for gas separation

    PubMed Central

    Wang, Xuerui; Chi, Chenglong; Zhang, Kang; Qian, Yuhong; Gupta, Krishna M.; Kang, Zixi; Jiang, Jianwen; Zhao, Dan

    2017-01-01

    It is highly desirable to reduce the membrane thickness in order to maximize the throughput and break the trade-off limitation for membrane-based gas separation. Two-dimensional membranes composed of atomic-thick graphene or graphene oxide nanosheets have gas transport pathways that are at least three orders of magnitude higher than the membrane thickness, leading to reduced gas permeation flux and impaired separation throughput. Here we present nm-thick molecular sieving membranes composed of porous two-dimensional metal-organic nanosheets. These membranes possess pore openings parallel to gas concentration gradient allowing high gas permeation flux and high selectivity, which are proven by both experiment and molecular dynamics simulation. Furthermore, the gas transport pathways of these membranes exhibit a reversed thermo-switchable feature, which is attributed to the molecular flexibility of the building metal-organic nanosheets. PMID:28205528

  8. Potential energy surface and rovibrational energy levels of the H2-CS van der Waals complex.

    PubMed

    Denis-Alpizar, Otoniel; Stoecklin, Thierry; Halvick, Philippe; Dubernet, Marie-Lise; Marinakis, Sarantos

    2012-12-21

    Owing to its large dipole, astrophysicists use carbon monosulfide (CS) as a tracer of molecular gas in the interstellar medium, often in regions where H(2) is the most abundant collider. Predictions of the rovibrational energy levels of the weakly bound complex CS-H(2) (not yet observed) and also of rate coefficients for rotational transitions of CS in collision with H(2) should help to interpret the observed spectra. This paper deals with the first goal, i.e., the calculation of the rovibrational energy levels. A new four-dimensional intermolecular potential energy surface for the H(2)-CS complex is presented. Ab initio potential energy calculations were carried out at the coupled-cluster level with single and double excitations and a perturbative treatment of triple excitations, using a quadruple-zeta basis set and midbond functions. The potential energy surface was obtained by an analytic fit of the ab initio data. The equilibrium structure of the H(2)-CS complex is found to be linear with the carbon pointing toward H(2) at the intermolecular separation of 8.6 a(o). The corresponding well depth is -173 cm(-1). The potential was used to calculate the rovibrational energy levels of the para-H(2)-CS and ortho-H(2)-CS complexes. The present work provides the first theoretical predictions of these levels. The calculated dissociation energies are found to be 35.9 cm(-1) and 49.9 cm(-1), respectively, for the para and ortho complexes. The second virial coefficient for the H(2)-CS pair has also been calculated for a large range of temperature. These results could be used to assign future experimental spectra and to check the accuracy of the potential energy surface.

  9. Computational investigation of noble gas adsorption and separation by nanoporous materials.

    SciTech Connect

    Allendorf, Mark D.; Sanders, Joseph C.; Greathouse, Jeffery A.

    2008-10-01

    Molecular simulations are used to assess the ability of metal-organic framework (MOF) materials to store and separate noble gases. Specifically, grand canonical Monte Carlo simulation techniques are used to predict noble gas adsorption isotherms at room temperature. Experimental trends of noble gas inflation curves of a Zn-based material (IRMOF-1) are matched by the simulation results. The simulations also predict that IRMOF-1 selectively adsorbs Xe atoms in Xe/Kr and Xe/Ar mixtures at total feed gas pressures of 1 bar (14.7 psia) and 10 bar (147 psia). Finally, simulations of a copper-based MOF (Cu-BTC) predict this material's ability to selectively adsorb Xe and Kr atoms when present in trace amounts in atmospheric air samples. These preliminary results suggest that Cu-BTC may be an ideal candidate for the pre-concentration of noble gases from air samples. Additional simulations and experiments are needed to determine the saturation limit of Cu-BTC for xenon, and whether any krypton atoms would remain in the Cu-BTC pores upon saturation.

  10. H2S mediated thermal and photochemical methane activation

    PubMed Central

    Baltrusaitis, Jonas; de Graaf, Coen; Broer, Ria; Patterson, Eric

    2013-01-01

    Sustainable, low temperature methods of natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) in mixture with methane, CH4, altogether deemed as sub-quality or “sour” gas. We propose a unique method for activating this “sour” gas to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3, and an energy carrier, such as H2. For this purpose, we computationally investigated H2S mediated methane activation to form a reactive CH3SH species via direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4+H2S complex results in a barrier-less relaxation via a conical intersection to form a ground state CH3SH+H2 complex. The resulting CH3SH can further be heterogeneously coupled over acidic catalysts to form higher hydrocarbons while the H2 can be used as a fuel. This process is very different from a conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced controllability over the process conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the currently industrially used methane steam reforming (SMR). PMID:24150813

  11. Heat Transfer Characteristics of Liquid-Driven Swirl Boiling Liquid/Gas Separator under Reduced Gravity

    NASA Astrophysics Data System (ADS)

    Oinuma, Ryoji; Nguyen, Ngoc; Dickes, Neil; Kurwitz, Richard C.; Best, Frederick R.

    2009-03-01

    Under reduced gravity conditions, conventional gravity-assisted steam generators do not function properly and shear-driven or swirl type of devices must be used. Once-through boilers with special inserts such as twisted-tapes or swirl devices and rotating boilers have been previously studied. The once-through boiler requires a liquid-vapor phase separator due to the inability to vaporize all liquid completely to avoid burn-out. These devices also encounter instabilities due to the sudden formation or collapse of vapor. The rotating boiler requires a large power input to operate and has less reliability due to moving parts and dynamic seals at high temperature. A liquid-driven vortex boiling separator is categorized as a shear-driven boiler, but creates centripetal-driven buoyancy forces to form a gas-liquid vortex by injecting liquid tangentially along the inner wall of the cylinder rather than rotating the body itself. The vortex boiling separator eliminates the disadvantages of devices mentioned above, having a low pressure drop, no moving parts and generating dry vapor at its outlet. Texas A&M University carried out a reduced gravity flight experiment on the NASA C-9 aircraft to investigate the heat transfer characteristics and performance based on similar devices developed at Texas A&M.

  12. Improved micromachined column design and fluidic interconnects for programmed high-temperature gas chromatography separations.

    PubMed

    Gaddes, David; Westland, Jessica; Dorman, Frank L; Tadigadapa, Srinivas

    2014-07-04

    This work focuses on the development and experimental evaluation of micromachined chromatographic columns for use in a commercial gas chromatography (GC) system. A vespel/graphite ferrule based compression sealing technique is presented using which leak-proof fluidic interconnection between the inlet tubing and the microchannel was achieved. This sealing technique enabled separation at temperatures up to 350°C on a μGC column. This paper reports the first high-temperature separations in microfabricated chromatographic columns at these temperatures. A 2m microfabricated column using a double Archimedean spiral design with a square cross-section of 100μm×100μm has been developed using silicon microfabrication techniques. The microfabricated column was benchmarked against a 2m 100μm diameter commercial column and the performance between the two columns was evaluated in tests performed under identical conditions. High temperature separations of simulated distillation (ASTM2887) and polycyclic aromatic hydrocarbons (EPA8310) were performed using the μGC column in temperature programmed mode. The demonstrated μGC column along with the high temperature fixture offers one more solution toward potentially realizing a portable μGC device for the detection of semi-volatile environmental pollutants and explosives without the thermal limitations reported to date with μGC columns using epoxy based interconnect technology.

  13. Carbon molecular sieve membranes on porous composite tubular supports for high performance gas separations

    SciTech Connect

    Lee, Pyung -Soo; Bhave, Ramesh R.; Nam, Seung -Eun; Kim, Daejin

    2016-01-11

    Thin carbon molecular sieve membranes (<500 nm) were fabricated inside of long geometry (9 inch) of stainless steel tubes with all welded construction. Alumina intermediate layer on porous stainless steel tube support was used to reduce effective support pore size and to provide a more uniform surface roughness. Novolac phenolic resin solution was then coated on the inside of porous stainless steel tube by slip casting while their viscosities were controlled from 5 centipoises to 30 centipoises. Carbonization was carried out at 700 °C in which thermal stress was minimized and high quality carbon films were prepared. The highest separation performance characteristics were obtained using 20 cP phenolic resin solutions. The fabricated CMSM showed good separation factor for He/N2 462, CO2/N2 97, and O2/N2 15.4. As the viscosity of polymer precursor solution was reduced from 20 cP to 15 cP, gas permeance values almost doubled with somewhat lower separation factor He/N2 156, CO2/N2 88, and O2/N2 7.7.

  14. Comprehensive three-dimensional gas chromatography mass spectrometry separation of diesel.

    PubMed

    Wang, Frank Cheng-Yu

    2017-03-17

    Diesel, a complex hydrocarbon mixture, was examined using comprehensive two-dimensional gas chromatography (GC×GC) and a field ionization mass spectrometer (FIMS), which preferentially yields molecular ions, providing an extra dimension for component separation. Molecular ions collected at low mass resolution can be assigned an NM-class (Nominal Mass-class) value that does not completely express hydrogen deficiency. In contrast to formulae and Z-class assignments that are possible from ultrahigh mass resolution, NM-class assignments are not unambiguous; however, the separation provided by GC×GC can result in coelution of components that differ in NM-class. Hence, compounds that are unresolved by GC×GC separation can be resolved by FIMS provided they differ in mass. This technique allows for easy, automated data processing, evaluation of coelution on quantitative analysis (e.g., using FID) and the identification of additional chemical species and structures. The development of GC×GC×MS creates new opportunities to improve the ability to determine hydrocarbon composition and structure in complex petroleum and refined petroleum products.

  15. Membrane gas separation. January 1970-May 1981 (citations from the Engineering Index Data Base). Report for Jan 70-May 81

    SciTech Connect

    Not Available

    1981-05-01

    This retrospective bibliography discusses the current literature on gas separation and purification using polymeric and metallic membranes. Included are topics such as isotope separation, osmotic techniques, reverse osmosis and preparation of membranes for specific separation processes. The permeability of polymer membranes is discussed in terms of physical properties of the membrane as well as its molecular structure. The selectivity of polymeric films for a variety of gases is also considered. (Contains 51 citations fully indexed and including a title list.)

  16. Membrane gas separation. January 1976-May 1981 (citations from the Energy Data Base). Report for Jan 76-May 81

    SciTech Connect

    Not Available

    1981-05-01

    This retrospective bibliography discusses the current literature on gas separation and purification using polymeric and metallic membranes. Included are topics such as isotope separation, osmotic techniques, reverse osmosis and preparation of membranes for specific separation processes. The permeability of polymer membranes is discussed in terms of physical properties of the membrane as well as its molecular structure. The selectivity of polymeric films for a variety of gases is also considered. (Contains 65 citations fully indexed and including a title list.)

  17. Membrane gas separation. January 1970-May 1981 (citations from the NTIS data base). Report for Jan 70-May 81

    SciTech Connect

    Not Available

    1981-05-01

    This retrospective bibliography discusses the current literature on gas separation and purification using polymeric and metallic membranes. Included are topics such as isotope separation, osmotic techniques, reverse osmosis, and preparation of membranes for specific separation processes. The permeability of polymer membranes is discussed in terms of physical properties, of the membrane as well as its molecular structure. The selectivity of polymeric films for a variety of gases is also considered. (Contains 78 citations fully indexed and including a title list.)

  18. A New Parameterization of H2SO4/H2O Aerosol Composition: Atmospheric Implications

    NASA Technical Reports Server (NTRS)

    Tabazadeh, Azadeh; Toon, Owen B.; Clegg, Simon L.; Hamill, Patrick

    1997-01-01

    Recent results from a thermodynamic model of aqueous sulfuric acid are used to derive a new parameterization for the variation of sulfuric acid aerosol composition with temperature and relative humidity. This formulation is valid for relative humidities above 1 % in the temperature range of 185 to 260 K. An expression for calculating the vapor pressure of supercooled liquid water, consistent with the sulfuric acid model, is also presented. We show that the Steele and Hamill [1981] formulation underestimates the water partial pressure over aqueous H2SOI solutions by up to 12% at low temperatures. This difference results in a corresponding underestimate of the H2SO4 concentration in the aerosol by about 6 % of the weight percent at approximately 190 K. In addition, the relation commonly used for estimating the vapor pressure of H2O over supercooled liquid water differs by up to 10 % from our derived expression. The combined error can result in a 20 % underestimation of water activity over a H2SO4 solution droplet in the stratosphere, which has implications for the parameterization of heterogeneous reaction rates in stratospheric sulfuric acid aerosols. The influence of aerosol composition on the rate of homogeneous ice nucleation from a H2SO4 solution droplet is also discussed. This parameterization can also be used for homogeneous gas phase nucleation calculations of H2SO4 solution droplets under various environmental conditions such as in aircraft exhaust or in volcanic plumes.

  19. The effect of H2O gas on volatilities of planet-forming major elements. I - Experimental determination of thermodynamic properties of Ca-, Al-, and Si-hydroxide gas molecules and its application to the solar nebula

    NASA Technical Reports Server (NTRS)

    Hashimoto, Akihiko

    1992-01-01

    The vapor pressures of Ca(OH)2(g), Al(OH)3(g), and Si(OH)4(g) molecules in equilibrium with solid calcium-, aluminum, and silicon-oxides, respectively, were determined, and were used to derive the heats of formation and entropies of these species, which are expected to be abundant under the currently postulated physical conditions in the primordial solar nebula. These data, in conjunction with thermodynamic data from literature, were used to calculate the relative abundances of M, MO(x), and M(OH)n gas species and relative volatilities of Fe, Mg, Si, Ca, and Al for ranges of temperature, total pressure, and H/O abundance ratio corresponding to the plausible ranges of physical conditions in the solar nebula. The results are used to explain how Ca and Al could have evaporated from Ca,Al-rich inclusions in carbonaceous chondrites, while Si, Mg, and Fe condensed onto them during the preaccretion alteration of CAIs.

  20. Unusual Recognition and Separation of Hydrated Metal Sulfates [M2(μ-SO4)2(H2O)n, M = Zn(II), Cd(II), Co(II), Mn(II)] by a Ditopic Receptor.

    PubMed

    Ghosh, Tamal Kanti; Dutta, Ranjan; Ghosh, Pradyut

    2016-04-04

    A ditopic receptor L1, having metal binding bis(2-picolyl) donor and anion binding urea group, is synthesized and explored toward metal sulfate recognition via formation of dinuclear assembly, (L1)2M2(SO4)2. Mass spectrometric analysis, (1)H-DOSY NMR, and crystal structure analysis reveal the existence of a dinuclear assembly of MSO4 with two units of L1. (1)H NMR study reveals significant downfield chemical shift of -NH protons of urea moiety of L1 selectively with metal sulfates (e.g., ZnSO4, CdSO4) due to second-sphere interactions of sulfate with the urea moiety. Variable-temperature (1)H NMR studies suggest the presence of intramolecular hydrogen bonding interaction toward metal sulfate recognition in solution state, whereas intermolecular H-bonding interactions are observed in solid state. In contrast, anions in their tetrabutylammonium salts fail to interact with the urea -NH probably due to poor acidity of the tertiary butyl urea group of L1. Metal sulfate binding selectivity in solution is further supported by isothermal titration calorimetric studies of L1 with different Zn salts in dimethyl sulfoxide (DMSO), where a binding affinity is observed for ZnSO4 (Ka = 1.23 × 10(6)), which is 30- to 50-fold higher than other Zn salts having other counteranions in DMSO. Sulfate salts of Cd(II)/Co(II) also exhibit binding constants in the order of ∼1 × 10(6) as in the case of ZnSO4. Positive role of the urea unit in the selectivity is confirmed by studying a model ligand L2, which is devoid of anion recognition urea unit. Structural characterization of four MSO4 [M = Zn(II), Cd(II), Co(II), Mn(II)] complexes of L1, that is, complex 1, [(L1)2(Zn)2(μ-SO4)2]; complex 2, [(L1)2(H2O)2(Cd)2(μ-SO4)2]; complex 3, [(L1)2(H2O)2(Co)2(μ-SO4)2]; and complex 4, [(L1)2(H2O)2(Mn)2(μ-SO4)2], reveal the formation of sulfate-bridged eight-membered crownlike binuclear complexes, similar to one of the concentration-dependent dimeric forms of MSO4 as observed in solid state